diff --git a/lib/shared/messages/create-sidebar-message-spec.js b/lib/shared/messages/create-sidebar-message-spec.js
--- a/lib/shared/messages/create-sidebar-message-spec.js
+++ b/lib/shared/messages/create-sidebar-message-spec.js
@@ -10,7 +10,6 @@
   type RobotextParams,
 } from './message-spec.js';
 import { joinResult } from './utils.js';
-import type { PlatformDetails } from '../../types/device-types.js';
 import { messageTypes } from '../../types/message-types-enum.js';
 import type {
   MessageInfo,
@@ -22,7 +21,6 @@
   type RawCreateSidebarMessageInfo,
   rawCreateSidebarMessageInfoValidator,
 } from '../../types/messages/create-sidebar.js';
-import type { RawUnsupportedMessageInfo } from '../../types/messages/unsupported.js';
 import type { NotifTexts } from '../../types/notif-types.js';
 import type { ThreadInfo } from '../../types/thread-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
@@ -32,7 +30,6 @@
   pluralizeEntityText,
 } from '../../utils/entity-text.js';
 import { notifTextsForSidebarCreation } from '../notif-utils.js';
-import { hasMinCodeVersion } from '../version-utils.js';
 
 export const createSidebarMessageSpec: MessageSpec<
   CreateSidebarMessageData,
@@ -158,26 +155,6 @@
     return ET`${creator} ${text}`;
   },
 
-  shimUnsupportedMessageInfo(
-    rawMessageInfo: RawCreateSidebarMessageInfo,
-    platformDetails: ?PlatformDetails,
-  ): RawCreateSidebarMessageInfo | RawUnsupportedMessageInfo {
-    if (hasMinCodeVersion(platformDetails, { native: 75 })) {
-      return rawMessageInfo;
-    }
-    const { id } = rawMessageInfo;
-    invariant(id !== null && id !== undefined, 'id should be set on server');
-    return {
-      type: messageTypes.UNSUPPORTED,
-      id,
-      threadID: rawMessageInfo.threadID,
-      creatorID: rawMessageInfo.creatorID,
-      time: rawMessageInfo.time,
-      robotext: 'created a thread',
-      unsupportedMessageInfo: rawMessageInfo,
-    };
-  },
-
   unshimMessageInfo(
     unwrapped: RawCreateSidebarMessageInfo,
   ): RawCreateSidebarMessageInfo {
diff --git a/lib/shared/messages/sidebar-source-message-spec.js b/lib/shared/messages/sidebar-source-message-spec.js
--- a/lib/shared/messages/sidebar-source-message-spec.js
+++ b/lib/shared/messages/sidebar-source-message-spec.js
@@ -9,7 +9,6 @@
   type RawMessageInfoFromServerDBRowParams,
 } from './message-spec.js';
 import { joinResult } from './utils.js';
-import type { PlatformDetails } from '../../types/device-types.js';
 import { messageTypes } from '../../types/message-types-enum.js';
 import {
   type RawSidebarSourceMessageInfo,
@@ -22,7 +21,6 @@
 import type { RawUnsupportedMessageInfo } from '../../types/messages/unsupported.js';
 import type { NotifTexts } from '../../types/notif-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
-import { hasMinCodeVersion } from '../version-utils.js';
 
 export const sidebarSourceMessageSpec: MessageSpec<
   SidebarSourceMessageData,
@@ -132,12 +130,8 @@
 
   shimUnsupportedMessageInfo(
     rawMessageInfo: RawSidebarSourceMessageInfo,
-    platformDetails: ?PlatformDetails,
   ): RawSidebarSourceMessageInfo | RawUnsupportedMessageInfo {
-    if (
-      hasMinCodeVersion(platformDetails, { native: 75 }) &&
-      rawMessageInfo.sourceMessage
-    ) {
+    if (rawMessageInfo.sourceMessage) {
       return rawMessageInfo;
     }
     const { id } = rawMessageInfo;
diff --git a/lib/shared/messages/update-relationship-message-spec.js b/lib/shared/messages/update-relationship-message-spec.js
--- a/lib/shared/messages/update-relationship-message-spec.js
+++ b/lib/shared/messages/update-relationship-message-spec.js
@@ -8,13 +8,11 @@
   type MessageSpec,
 } from './message-spec.js';
 import { assertSingleMessageInfo } from './utils.js';
-import type { PlatformDetails } from '../../types/device-types.js';
 import { messageTypes } from '../../types/message-types-enum.js';
 import type {
   MessageInfo,
   ClientDBMessageInfo,
 } from '../../types/message-types.js';
-import type { RawUnsupportedMessageInfo } from '../../types/messages/unsupported.js';
 import {
   type RawUpdateRelationshipMessageInfo,
   type UpdateRelationshipMessageData,
@@ -25,7 +23,6 @@
 import type { ThreadInfo } from '../../types/thread-types.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import { ET, type EntityText } from '../../utils/entity-text.js';
-import { hasMinCodeVersion } from '../version-utils.js';
 
 export const updateRelationshipMessageSpec: MessageSpec<
   UpdateRelationshipMessageData,
@@ -128,26 +125,6 @@
     );
   },
 
-  shimUnsupportedMessageInfo(
-    rawMessageInfo: RawUpdateRelationshipMessageInfo,
-    platformDetails: ?PlatformDetails,
-  ): RawUpdateRelationshipMessageInfo | RawUnsupportedMessageInfo {
-    if (hasMinCodeVersion(platformDetails, { native: 71 })) {
-      return rawMessageInfo;
-    }
-    const { id } = rawMessageInfo;
-    invariant(id !== null && id !== undefined, 'id should be set on server');
-    return {
-      type: messageTypes.UNSUPPORTED,
-      id,
-      threadID: rawMessageInfo.threadID,
-      creatorID: rawMessageInfo.creatorID,
-      time: rawMessageInfo.time,
-      robotext: 'performed a relationship action',
-      unsupportedMessageInfo: rawMessageInfo,
-    };
-  },
-
   unshimMessageInfo(
     unwrapped: RawUpdateRelationshipMessageInfo,
   ): RawUpdateRelationshipMessageInfo {