diff --git a/src/ContentMessages.tsx b/src/ContentMessages.tsx
index 8b0ddc8368..9a2b9ac79c 100644
--- a/src/ContentMessages.tsx
+++ b/src/ContentMessages.tsx
@@ -19,12 +19,13 @@ limitations under the License.
 import React from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { IUploadOpts } from "matrix-js-sdk/src/@types/requests";
-import { MsgType, RelationType } from "matrix-js-sdk/src/@types/event";
+import { MsgType } from "matrix-js-sdk/src/@types/event";
 import encrypt from "browser-encrypt-attachment";
 import extractPngChunks from "png-chunks-extract";
 import { IAbortablePromise, IImageInfo } from "matrix-js-sdk/src/@types/partials";
 import { logger } from "matrix-js-sdk/src/logger";
 import { IEventRelation, ISendEventResponse } from "matrix-js-sdk/src/matrix";
+import { THREAD_RELATION_TYPE } from "matrix-js-sdk/src/models/thread";
 
 import { IEncryptedFile, IMediaEventInfo } from "./customisations/models/IMediaEventContent";
 import dis from './dispatcher/dispatcher';
@@ -658,7 +659,7 @@ export default class ContentMessages {
             return promBefore;
         }).then(function() {
             if (upload.canceled) throw new UploadCanceledError();
-            const threadId = relation?.rel_type === RelationType.Thread
+            const threadId = relation?.rel_type === THREAD_RELATION_TYPE.name
                 ? relation.event_id
                 : null;
             const prom = matrixClient.sendMessage(roomId, threadId, content);
diff --git a/src/components/structures/ThreadPanel.tsx b/src/components/structures/ThreadPanel.tsx
index 98c1fff835..30669a8eec 100644
--- a/src/components/structures/ThreadPanel.tsx
+++ b/src/components/structures/ThreadPanel.tsx
@@ -17,15 +17,18 @@ limitations under the License.
 import React, { useContext, useEffect, useRef, useState } from 'react';
 import { EventTimelineSet } from 'matrix-js-sdk/src/models/event-timeline-set';
 import { Room } from 'matrix-js-sdk/src/models/room';
-import { RelationType } from 'matrix-js-sdk/src/@types/event';
 import { MatrixClient } from 'matrix-js-sdk/src/client';
 import {
     Filter,
     IFilterDefinition,
-    UNSTABLE_FILTER_RELATED_BY_SENDERS,
-    UNSTABLE_FILTER_RELATED_BY_REL_TYPES,
 } from 'matrix-js-sdk/src/filter';
-import { Thread, ThreadEvent } from 'matrix-js-sdk/src/models/thread';
+import {
+    FILTER_RELATED_BY_REL_TYPES,
+    FILTER_RELATED_BY_SENDERS,
+    Thread,
+    ThreadEvent,
+    THREAD_RELATION_TYPE,
+} from 'matrix-js-sdk/src/models/thread';
 import { EventTimeline } from 'matrix-js-sdk/src/models/event-timeline';
 
 import BaseCard from "../views/right_panel/BaseCard";
@@ -54,13 +57,13 @@ export async function getThreadTimelineSet(
         const definition: IFilterDefinition = {
             "room": {
                 "timeline": {
-                    [UNSTABLE_FILTER_RELATED_BY_REL_TYPES.name]: [RelationType.Thread],
+                    [FILTER_RELATED_BY_REL_TYPES.name]: [THREAD_RELATION_TYPE.name],
                 },
             },
         };
 
         if (filterType === ThreadFilterType.My) {
-            definition.room.timeline[UNSTABLE_FILTER_RELATED_BY_SENDERS.name] = [myUserId];
+            definition.room.timeline[FILTER_RELATED_BY_SENDERS.name] = [myUserId];
         }
 
         filter.setDefinition(definition);
diff --git a/src/components/structures/ThreadView.tsx b/src/components/structures/ThreadView.tsx
index 8a00bbdc65..374ff1a2e4 100644
--- a/src/components/structures/ThreadView.tsx
+++ b/src/components/structures/ThreadView.tsx
@@ -15,8 +15,7 @@ limitations under the License.
 */
 
 import React, { createRef, KeyboardEvent } from 'react';
-import { Thread, ThreadEvent } from 'matrix-js-sdk/src/models/thread';
-import { RelationType } from 'matrix-js-sdk/src/@types/event';
+import { Thread, ThreadEvent, THREAD_RELATION_TYPE } from 'matrix-js-sdk/src/models/thread';
 import { Room } from 'matrix-js-sdk/src/models/room';
 import { IEventRelation, MatrixEvent } from 'matrix-js-sdk/src/models/event';
 import { TimelineWindow } from 'matrix-js-sdk/src/timeline-window';
@@ -181,7 +180,7 @@ export default class ThreadView extends React.Component<IProps, IState> {
             this.setState({
                 thread,
                 lastThreadReply: thread.lastReply((ev: MatrixEvent) => {
-                    return ev.isRelation(RelationType.Thread) && !ev.status;
+                    return ev.isRelation(THREAD_RELATION_TYPE.name) && !ev.status;
                 }),
             }, async () => {
                 thread.emit(ThreadEvent.ViewThread);
@@ -201,7 +200,7 @@ export default class ThreadView extends React.Component<IProps, IState> {
         if (this.state.thread) {
             this.setState({
                 lastThreadReply: this.state.thread.lastReply((ev: MatrixEvent) => {
-                    return ev.isRelation(RelationType.Thread) && !ev.status;
+                    return ev.isRelation(THREAD_RELATION_TYPE.name) && !ev.status;
                 }),
             });
         }
@@ -288,7 +287,7 @@ export default class ThreadView extends React.Component<IProps, IState> {
 
     private get threadRelation(): IEventRelation {
         return {
-            "rel_type": RelationType.Thread,
+            "rel_type": THREAD_RELATION_TYPE.name,
             "event_id": this.state.thread?.id,
             "m.in_reply_to": {
                 "event_id": this.state.lastThreadReply?.getId() ?? this.state.thread?.id,
diff --git a/src/components/views/location/shareLocation.ts b/src/components/views/location/shareLocation.ts
index c7ea31bb26..b2632fa0f8 100644
--- a/src/components/views/location/shareLocation.ts
+++ b/src/components/views/location/shareLocation.ts
@@ -14,12 +14,12 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { RelationType } from "matrix-js-sdk/src/@types/event";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { makeLocationContent } from "matrix-js-sdk/src/content-helpers";
 import { logger } from "matrix-js-sdk/src/logger";
 import { IEventRelation } from "matrix-js-sdk/src/models/event";
 import { LocationAssetType } from "matrix-js-sdk/src/@types/location";
+import { THREAD_RELATION_TYPE } from "matrix-js-sdk/src/models/thread";
 
 import { _t } from "../../../languageHandler";
 import Modal from "../../../Modal";
@@ -41,7 +41,7 @@ export const shareLocation = (
 ) => async (uri: string, ts: number) => {
     if (!uri) return false;
     try {
-        const threadId = relation?.rel_type === RelationType.Thread ? relation.event_id : null;
+        const threadId = relation?.rel_type === THREAD_RELATION_TYPE.name ? relation.event_id : null;
         const assetType = shareType === LocationShareType.Pin ? LocationAssetType.Pin : LocationAssetType.Self;
         await client.sendMessage(roomId, threadId, makeLocationContent(undefined, uri, ts, undefined, assetType));
     } catch (e) {
diff --git a/src/components/views/rooms/MessageComposer.tsx b/src/components/views/rooms/MessageComposer.tsx
index 2ea6740ea8..6bd41fcf93 100644
--- a/src/components/views/rooms/MessageComposer.tsx
+++ b/src/components/views/rooms/MessageComposer.tsx
@@ -19,8 +19,9 @@ import classNames from 'classnames';
 import { IEventRelation, MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { Room } from "matrix-js-sdk/src/models/room";
 import { RoomMember } from "matrix-js-sdk/src/models/room-member";
-import { EventType, RelationType } from 'matrix-js-sdk/src/@types/event';
+import { EventType } from 'matrix-js-sdk/src/@types/event';
 import { Optional } from "matrix-events-sdk";
+import { THREAD_RELATION_TYPE } from 'matrix-js-sdk/src/models/thread';
 
 import { _t } from '../../../languageHandler';
 import { MatrixClientPeg } from '../../../MatrixClientPeg';
@@ -258,7 +259,7 @@ export default class MessageComposer extends React.Component<IProps, IState> {
 
     private renderPlaceholderText = () => {
         if (this.props.replyToEvent) {
-            const replyingToThread = this.props.relation?.rel_type === RelationType.Thread;
+            const replyingToThread = this.props.relation?.rel_type === THREAD_RELATION_TYPE.name;
             if (replyingToThread && this.props.e2eStatus) {
                 return _t('Reply to encrypted thread…');
             } else if (replyingToThread) {
@@ -426,7 +427,7 @@ export default class MessageComposer extends React.Component<IProps, IState> {
             />;
         }
 
-        const threadId = this.props.relation?.rel_type === RelationType.Thread
+        const threadId = this.props.relation?.rel_type === THREAD_RELATION_TYPE.name
             ? this.props.relation.event_id
             : null;
 
diff --git a/src/components/views/rooms/MessageComposerButtons.tsx b/src/components/views/rooms/MessageComposerButtons.tsx
index 4dee986b03..fc7dd1ed84 100644
--- a/src/components/views/rooms/MessageComposerButtons.tsx
+++ b/src/components/views/rooms/MessageComposerButtons.tsx
@@ -20,7 +20,7 @@ import { M_POLL_START } from "matrix-events-sdk";
 import React, { createContext, ReactElement, useContext, useRef } from 'react';
 import { Room } from 'matrix-js-sdk/src/models/room';
 import { MatrixClient } from 'matrix-js-sdk/src/client';
-import { RelationType } from 'matrix-js-sdk/src/@types/event';
+import { THREAD_RELATION_TYPE } from 'matrix-js-sdk/src/models/thread';
 
 import { _t } from '../../../languageHandler';
 import AccessibleTooltipButton from "../elements/AccessibleTooltipButton";
@@ -318,7 +318,7 @@ class PollButton extends React.PureComponent<IPollButtonProps> {
                 },
             );
         } else {
-            const threadId = this.props.relation?.rel_type === RelationType.Thread
+            const threadId = this.props.relation?.rel_type === THREAD_RELATION_TYPE.name
                 ? this.props.relation.event_id
                 : null;
 
@@ -339,7 +339,7 @@ class PollButton extends React.PureComponent<IPollButtonProps> {
 
     public render() {
         // do not allow sending polls within threads at this time
-        if (this.props.relation?.rel_type === RelationType.Thread) return null;
+        if (this.props.relation?.rel_type === THREAD_RELATION_TYPE.name) return null;
 
         return (
             <CollapsibleButton
diff --git a/src/components/views/rooms/SendMessageComposer.tsx b/src/components/views/rooms/SendMessageComposer.tsx
index 35a956f09d..1938748e1c 100644
--- a/src/components/views/rooms/SendMessageComposer.tsx
+++ b/src/components/views/rooms/SendMessageComposer.tsx
@@ -22,6 +22,7 @@ import { EventType, RelationType } from "matrix-js-sdk/src/@types/event";
 import { logger } from "matrix-js-sdk/src/logger";
 import { Room } from 'matrix-js-sdk/src/models/room';
 import { Composer as ComposerEvent } from "matrix-analytics-events/types/typescript/Composer";
+import { THREAD_RELATION_TYPE } from 'matrix-js-sdk/src/models/thread';
 
 import dis from '../../../dispatcher/dispatcher';
 import EditorModel from '../../../editor/model';
@@ -132,7 +133,7 @@ export function createMessageContent(
         addReplyToMessageContent(content, replyToEvent, {
             permalinkCreator,
             includeLegacyFallback: includeReplyLegacyFallback,
-            inThread: relation?.rel_type === RelationType.Thread,
+            inThread: relation?.rel_type === THREAD_RELATION_TYPE.name,
         });
     }
 
@@ -204,7 +205,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
     }
 
     public componentDidUpdate(prevProps: ISendMessageComposerProps): void {
-        const replyingToThread = this.props.relation?.key === RelationType.Thread;
+        const replyingToThread = this.props.relation?.key === THREAD_RELATION_TYPE.name;
         const differentEventTarget = this.props.relation?.event_id !== prevProps.relation?.event_id;
 
         const threadChanged = replyingToThread && (differentEventTarget);
@@ -221,7 +222,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
         if (this.editorRef.current?.isComposing(event)) {
             return;
         }
-        const replyingToThread = this.props.relation?.key === RelationType.Thread;
+        const replyingToThread = this.props.relation?.key === THREAD_RELATION_TYPE.name;
         const action = getKeyBindingsManager().getMessageComposerAction(event);
         switch (action) {
             case KeyBindingAction.SendMessage:
@@ -358,7 +359,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
             eventName: "Composer",
             isEditing: false,
             isReply: !!this.props.replyToEvent,
-            inThread: this.props.relation?.rel_type === RelationType.Thread,
+            inThread: this.props.relation?.rel_type === THREAD_RELATION_TYPE.name,
         };
         if (posthogEvent.inThread) {
             const threadRoot = this.props.room.findEventById(this.props.relation.event_id);
@@ -383,7 +384,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
         if (!containsEmote(model) && isSlashCommand(this.model)) {
             const [cmd, args, commandText] = getSlashCommand(this.model);
             if (cmd) {
-                const threadId = this.props.relation?.rel_type === RelationType.Thread
+                const threadId = this.props.relation?.rel_type === THREAD_RELATION_TYPE.name
                     ? this.props.relation?.event_id
                     : null;
 
@@ -398,7 +399,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
                         addReplyToMessageContent(content, replyToEvent, {
                             permalinkCreator: this.props.permalinkCreator,
                             includeLegacyFallback: true,
-                            inThread: this.props.relation?.rel_type === RelationType.Thread,
+                            inThread: this.props.relation?.rel_type === THREAD_RELATION_TYPE.name,
                         });
                     }
                 } else {
@@ -434,7 +435,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
                 decorateStartSendingTime(content);
             }
 
-            const threadId = this.props.relation?.rel_type === RelationType.Thread
+            const threadId = this.props.relation?.rel_type === THREAD_RELATION_TYPE.name
                 ? this.props.relation.event_id
                 : null;
 
@@ -453,7 +454,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
                 if (containsEmoji(content, effect.emojis)) {
                     // For initial threads launch, chat effects are disabled
                     // see #19731
-                    const isNotThread = this.props.relation?.rel_type !== RelationType.Thread;
+                    const isNotThread = this.props.relation?.rel_type !== THREAD_RELATION_TYPE.name;
                     if (!SettingsStore.getValue("feature_thread") || isNotThread) {
                         dis.dispatch({ action: `effects.${effect.command}` });
                     }
@@ -497,7 +498,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
 
     private get editorStateKey() {
         let key = `mx_cider_state_${this.props.room.roomId}`;
-        if (this.props.relation?.rel_type === RelationType.Thread) {
+        if (this.props.relation?.rel_type === THREAD_RELATION_TYPE.name) {
             key += `_${this.props.relation.event_id}`;
         }
         return key;
@@ -508,7 +509,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
     }
 
     private restoreStoredEditorState(partCreator: PartCreator): Part[] {
-        const replyingToThread = this.props.relation?.key === RelationType.Thread;
+        const replyingToThread = this.props.relation?.key === THREAD_RELATION_TYPE.name;
         if (replyingToThread) {
             return null;
         }
@@ -600,7 +601,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
     };
 
     render() {
-        const threadId = this.props.relation?.rel_type === RelationType.Thread
+        const threadId = this.props.relation?.rel_type === THREAD_RELATION_TYPE.name
             ? this.props.relation.event_id
             : null;
         return (
diff --git a/src/stores/widgets/StopGapWidgetDriver.ts b/src/stores/widgets/StopGapWidgetDriver.ts
index f2f42d5cbf..4fa9d6d9a6 100644
--- a/src/stores/widgets/StopGapWidgetDriver.ts
+++ b/src/stores/widgets/StopGapWidgetDriver.ts
@@ -29,10 +29,11 @@ import {
     WidgetEventCapability,
     WidgetKind,
 } from "matrix-widget-api";
-import { EventType, RelationType } from "matrix-js-sdk/src/@types/event";
+import { EventType } from "matrix-js-sdk/src/@types/event";
 import { IContent, IEvent, MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { Room } from "matrix-js-sdk/src/models/room";
 import { logger } from "matrix-js-sdk/src/logger";
+import { THREAD_RELATION_TYPE } from "matrix-js-sdk/src/models/thread";
 
 import { iterableDiff, iterableIntersection } from "../../utils/iterables";
 import { MatrixClientPeg } from "../../MatrixClientPeg";
@@ -169,7 +170,7 @@ export class StopGapWidgetDriver extends WidgetDriver {
                     if (containsEmoji(content, effect.emojis)) {
                         // For initial threads launch, chat effects are disabled
                         // see #19731
-                        const isNotThread = content["m.relates_to"].rel_type !== RelationType.Thread;
+                        const isNotThread = content["m.relates_to"].rel_type !== THREAD_RELATION_TYPE.name;
                         if (!SettingsStore.getValue("feature_thread") || isNotThread) {
                             dis.dispatch({ action: `effects.${effect.command}` });
                         }
diff --git a/src/utils/Reply.ts b/src/utils/Reply.ts
index 3c696e9aee..b43b6cce60 100644
--- a/src/utils/Reply.ts
+++ b/src/utils/Reply.ts
@@ -15,9 +15,9 @@ limitations under the License.
 */
 
 import { IContent, MatrixEvent } from "matrix-js-sdk/src/models/event";
-import { RelationType } from "matrix-js-sdk/src/@types/event";
 import sanitizeHtml from "sanitize-html";
 import escapeHtml from "escape-html";
+import { THREAD_RELATION_TYPE } from "matrix-js-sdk/src/models/thread";
 
 import { PERMITTED_URL_SCHEMES } from "../HtmlUtils";
 import { makeUserPermalink, RoomPermalinkCreator } from "./permalinks/Permalinks";
@@ -163,7 +163,7 @@ export function makeReplyMixIn(ev?: MatrixEvent, inThread = false): RecursivePar
     if (ev.isThreadRelation) {
         mixin['m.relates_to'] = {
             ...mixin['m.relates_to'],
-            rel_type: RelationType.Thread,
+            rel_type: THREAD_RELATION_TYPE.name,
             event_id: ev.threadRootId,
         };
     }
diff --git a/test/components/structures/ThreadPanel-test.tsx b/test/components/structures/ThreadPanel-test.tsx
index 7f735171d7..4fea571968 100644
--- a/test/components/structures/ThreadPanel-test.tsx
+++ b/test/components/structures/ThreadPanel-test.tsx
@@ -18,10 +18,7 @@ import React from 'react';
 import { shallow, mount } from "enzyme";
 import {
     MatrixClient,
-    RelationType,
     Room,
-    UNSTABLE_FILTER_RELATED_BY_REL_TYPES,
-    UNSTABLE_FILTER_RELATED_BY_SENDERS,
 } from 'matrix-js-sdk/src/matrix';
 import { mocked } from 'jest-mock';
 import '../../skinned-sdk';
@@ -179,7 +176,7 @@ describe('ThreadPanel', () => {
                 const [filterKey, filter] = mocked(client).getOrCreateFilter.mock.calls[0];
                 expect(filterKey).toEqual(`THREAD_PANEL_${room.roomId}_${ThreadFilterType.All}`);
                 expect(filter.getDefinition().room.timeline).toEqual({
-                    [UNSTABLE_FILTER_RELATED_BY_REL_TYPES.name]: [RelationType.Thread],
+                    related_by_rel_types: ["m.thread"],
                 });
             });
 
@@ -189,8 +186,8 @@ describe('ThreadPanel', () => {
                 const [filterKey, filter] = mocked(client).getOrCreateFilter.mock.calls[0];
                 expect(filterKey).toEqual(`THREAD_PANEL_${room.roomId}_${ThreadFilterType.My}`);
                 expect(filter.getDefinition().room.timeline).toEqual({
-                    [UNSTABLE_FILTER_RELATED_BY_REL_TYPES.name]: [RelationType.Thread],
-                    [UNSTABLE_FILTER_RELATED_BY_SENDERS.name]: [aliceId],
+                    related_by_rel_types: ["m.thread"],
+                    related_by_senders: [aliceId],
                 });
             });
         });
diff --git a/test/components/views/rooms/SendMessageComposer-test.tsx b/test/components/views/rooms/SendMessageComposer-test.tsx
index cd98593385..1ae7b141f4 100644
--- a/test/components/views/rooms/SendMessageComposer-test.tsx
+++ b/test/components/views/rooms/SendMessageComposer-test.tsx
@@ -18,7 +18,6 @@ import React from "react";
 import { act } from "react-dom/test-utils";
 import { sleep } from "matrix-js-sdk/src/utils";
 import { mount } from 'enzyme';
-import { RelationType } from 'matrix-js-sdk/src/@types/event';
 
 import '../../../skinned-sdk'; // Must be first for skinning to work
 import SendMessageComposer, {
@@ -298,7 +297,7 @@ describe('<SendMessageComposer/>', () => {
                         placeholder=""
                         permalinkCreator={new MatrixToPermalinkConstructor() as any}
                         relation={{
-                            rel_type: RelationType.Thread,
+                            rel_type: "m.thread",
                             event_id: "myFakeThreadId",
                         }}
                         includeReplyLegacyFallback={false}
diff --git a/test/test-utils/threads.ts b/test/test-utils/threads.ts
index 1df62e51d7..ebed292eb5 100644
--- a/test/test-utils/threads.ts
+++ b/test/test-utils/threads.ts
@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { MatrixClient, MatrixEvent, RelationType, Room } from "matrix-js-sdk/src/matrix";
+import { MatrixClient, MatrixEvent, Room } from "matrix-js-sdk/src/matrix";
 import { Thread } from "matrix-js-sdk/src/models/thread";
 
 import { mkMessage, MessageEventProps } from "./test-utils";
@@ -25,7 +25,7 @@ export const makeThreadEvent = ({ rootEventId, replyToEventId, ...props }: Messa
     ...props,
     relatesTo: {
         event_id: rootEventId,
-        rel_type: RelationType.Thread,
+        rel_type: "m.thread",
         ['m.in_reply_to']: {
             event_id: replyToEventId,
         },
@@ -79,7 +79,7 @@ export const makeThreadEvents = ({
 
     rootEvent.setUnsigned({
         "m.relations": {
-            [RelationType.Thread]: {
+            "m.thread": {
                 latest_event: events[events.length - 1],
                 count: length,
                 current_user_participated: [...participantUserIds, authorId].includes(currentUserId),