fix: don't display message preview of thread (#31043)

src/stores/room-list/MessagePreviewStore.ts

@@ -31,6 +31,7 @@ import { ReactionEventPreview } from "./previews/ReactionEventPreview";
 import { UPDATE_EVENT } from "../AsyncStore";
 import { type IPreview } from "./previews/IPreview";
 import shouldHideEvent from "../../shouldHideEvent";
+import SettingsStore from "../../settings/SettingsStore";
 
 // Emitted event for when a room's preview has changed. First argument will the room for which
 // the change happened.
@@ -178,11 +179,14 @@ export class MessagePreviewStore extends AsyncStoreWithClient<EmptyObject> {
     private async generatePreview(room: Room, tagId?: TagID): Promise<void> {
         const events = [...room.getLiveTimeline().getEvents(), ...room.getPendingEvents()];
 
-        // add last reply from each thread
-        room.getThreads().forEach((thread: Thread): void => {
-            const lastReply = thread.lastReply();
-            if (lastReply) events.push(lastReply);
-        });
+        const isNewRoomListEnabled = SettingsStore.getValue("feature_new_room_list");
+        if (!isNewRoomListEnabled) {
+            // add last reply from each thread
+            room.getThreads().forEach((thread: Thread): void => {
+                const lastReply = thread.lastReply();
+                if (lastReply) events.push(lastReply);
+            });
+        }
 
         // sort events from oldest to newest
         events.sort((a: MatrixEvent, b: MatrixEvent) => {