diff --git a/lib/shared/messages/add-members-message-spec.js b/lib/shared/messages/add-members-message-spec.js
--- a/lib/shared/messages/add-members-message-spec.js
+++ b/lib/shared/messages/add-members-message-spec.js
@@ -25,7 +25,6 @@
 } from '../../types/messages/add-members.js';
 import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { NotifTexts } from '../../types/notif-types.js';
-import { threadTypeIsThick } from '../../types/thread-types-enum.js';
 import { threadIDIsThick } from '../../types/thread-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import {
@@ -35,6 +34,7 @@
 } from '../../utils/entity-text.js';
 import { values } from '../../utils/objects.js';
 import { notifRobotextForMessageInfo } from '../notif-utils.js';
+import { threadSpecs } from '../threads/thread-specs.js';
 
 function getAddMembersRobotext(messageInfo: AddMembersMessageInfo): EntityText {
   const users = messageInfo.addedMembers;
@@ -232,12 +232,18 @@
   showInMessagePreview: (
     messageInfo: AddMembersMessageInfo,
     params: ShowInMessagePreviewParams,
-  ) => threadTypeIsThick(params.threadInfo.type),
+  ) =>
+    threadSpecs[params.threadInfo.type].protocol
+      .membershipChangesShownInThreadPreview,
 
   getLastUpdatedTime: (
     rawMessageInfo: RawAddMembersMessageInfo,
     params: ShowInMessagePreviewParams,
-  ) => (threadTypeIsThick(params.threadInfo.type) ? rawMessageInfo.time : null),
+  ) =>
+    threadSpecs[params.threadInfo.type].protocol
+      .membershipChangesShownInThreadPreview
+      ? rawMessageInfo.time
+      : null,
 
   getMessageNotifyType: async (rawMessageInfo: RawAddMembersMessageInfo) =>
     threadIDIsThick(rawMessageInfo.threadID)
diff --git a/lib/shared/messages/join-thread-message-spec.js b/lib/shared/messages/join-thread-message-spec.js
--- a/lib/shared/messages/join-thread-message-spec.js
+++ b/lib/shared/messages/join-thread-message-spec.js
@@ -24,7 +24,6 @@
 } from '../../types/messages/join-thread.js';
 import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { NotifTexts } from '../../types/notif-types.js';
-import { threadTypeIsThick } from '../../types/thread-types-enum.js';
 import { threadIDIsThick } from '../../types/thread-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import {
@@ -33,6 +32,7 @@
   pluralizeEntityText,
 } from '../../utils/entity-text.js';
 import { values } from '../../utils/objects.js';
+import { threadSpecs } from '../threads/thread-specs.js';
 
 function getJoinThreadRobotext(
   joinerString: EntityText,
@@ -178,12 +178,18 @@
   showInMessagePreview: (
     messageInfo: JoinThreadMessageInfo,
     params: ShowInMessagePreviewParams,
-  ) => threadTypeIsThick(params.threadInfo.type),
+  ) =>
+    threadSpecs[params.threadInfo.type].protocol
+      .membershipChangesShownInThreadPreview,
 
   getLastUpdatedTime: (
     rawMessageInfo: RawJoinThreadMessageInfo,
     params: ShowInMessagePreviewParams,
-  ) => (threadTypeIsThick(params.threadInfo.type) ? rawMessageInfo.time : null),
+  ) =>
+    threadSpecs[params.threadInfo.type].protocol
+      .membershipChangesShownInThreadPreview
+      ? rawMessageInfo.time
+      : null,
 
   getMessageNotifyType: async (rawMessageInfo: RawJoinThreadMessageInfo) =>
     threadIDIsThick(rawMessageInfo.threadID)
diff --git a/lib/shared/messages/leave-thread-message-spec.js b/lib/shared/messages/leave-thread-message-spec.js
--- a/lib/shared/messages/leave-thread-message-spec.js
+++ b/lib/shared/messages/leave-thread-message-spec.js
@@ -24,7 +24,6 @@
 } from '../../types/messages/leave-thread.js';
 import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { NotifTexts } from '../../types/notif-types.js';
-import { threadTypeIsThick } from '../../types/thread-types-enum.js';
 import { threadIDIsThick } from '../../types/thread-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import {
@@ -33,6 +32,7 @@
   pluralizeEntityText,
 } from '../../utils/entity-text.js';
 import { values } from '../../utils/objects.js';
+import { threadSpecs } from '../threads/thread-specs.js';
 
 function getLeaveThreadRobotext(
   leaverString: EntityText,
@@ -178,12 +178,18 @@
   showInMessagePreview: (
     messageInfo: LeaveThreadMessageInfo,
     params: ShowInMessagePreviewParams,
-  ) => threadTypeIsThick(params.threadInfo.type),
+  ) =>
+    threadSpecs[params.threadInfo.type].protocol
+      .membershipChangesShownInThreadPreview,
 
   getLastUpdatedTime: (
     rawMessageInfo: RawLeaveThreadMessageInfo,
     params: ShowInMessagePreviewParams,
-  ) => (threadTypeIsThick(params.threadInfo.type) ? rawMessageInfo.time : null),
+  ) =>
+    threadSpecs[params.threadInfo.type].protocol
+      .membershipChangesShownInThreadPreview
+      ? rawMessageInfo.time
+      : null,
 
   getMessageNotifyType: async (rawMessageInfo: RawLeaveThreadMessageInfo) =>
     threadIDIsThick(rawMessageInfo.threadID)
diff --git a/lib/shared/messages/remove-members-message-spec.js b/lib/shared/messages/remove-members-message-spec.js
--- a/lib/shared/messages/remove-members-message-spec.js
+++ b/lib/shared/messages/remove-members-message-spec.js
@@ -25,7 +25,6 @@
 } from '../../types/messages/remove-members.js';
 import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { NotifTexts } from '../../types/notif-types.js';
-import { threadTypeIsThick } from '../../types/thread-types-enum.js';
 import { threadIDIsThick } from '../../types/thread-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import {
@@ -35,6 +34,7 @@
 } from '../../utils/entity-text.js';
 import { values } from '../../utils/objects.js';
 import { notifRobotextForMessageInfo } from '../notif-utils.js';
+import { threadSpecs } from '../threads/thread-specs.js';
 
 function getRemoveMembersRobotext(
   messageInfo: RemoveMembersMessageInfo,
@@ -238,13 +238,18 @@
     showInMessagePreview: (
       messageInfo: RemoveMembersMessageInfo,
       params: ShowInMessagePreviewParams,
-    ) => threadTypeIsThick(params.threadInfo.type),
+    ) =>
+      threadSpecs[params.threadInfo.type].protocol
+        .membershipChangesShownInThreadPreview,
 
     getLastUpdatedTime: (
       rawMessageInfo: RawRemoveMembersMessageInfo,
       params: ShowInMessagePreviewParams,
     ) =>
-      threadTypeIsThick(params.threadInfo.type) ? rawMessageInfo.time : null,
+      threadSpecs[params.threadInfo.type].protocol
+        .membershipChangesShownInThreadPreview
+        ? rawMessageInfo.time
+        : null,
 
     getMessageNotifyType: async (
       rawMessageInfo: RawRemoveMembersMessageInfo,
diff --git a/lib/shared/threads/protocols/dm-thread-protocol.js b/lib/shared/threads/protocols/dm-thread-protocol.js
--- a/lib/shared/threads/protocols/dm-thread-protocol.js
+++ b/lib/shared/threads/protocols/dm-thread-protocol.js
@@ -429,6 +429,8 @@
       threadID: threadInfo.id,
     };
   },
+
+  membershipChangesShownInThreadPreview: true,
 });
 
 export { dmThreadProtocol };
diff --git a/lib/shared/threads/protocols/keyserver-thread-protocol.js b/lib/shared/threads/protocols/keyserver-thread-protocol.js
--- a/lib/shared/threads/protocols/keyserver-thread-protocol.js
+++ b/lib/shared/threads/protocols/keyserver-thread-protocol.js
@@ -212,6 +212,8 @@
     } = input;
     return utils.keyserverSetThreadUnreadStatus(rest);
   },
+
+  membershipChangesShownInThreadPreview: false,
 });
 
 function mediaIDIsKeyserverID(mediaID: string): boolean {
diff --git a/lib/shared/threads/thread-spec.js b/lib/shared/threads/thread-spec.js
--- a/lib/shared/threads/thread-spec.js
+++ b/lib/shared/threads/thread-spec.js
@@ -184,6 +184,7 @@
     input: ProtocolSetThreadUnreadStatusInput,
     utils: SetThreadUnreadStatusUtils,
   ) => Promise<SetThreadUnreadStatusPayload>,
+  +membershipChangesShownInThreadPreview: boolean,
 };
 
 export type ThreadSpec = {