lib/pleroma/web/activity_pub/side_effects.ex

@@ -425,7 +425,14 @@ defp handle_update_object(
     orig_object = Object.get_by_ap_id(orig_object_ap_id)
     orig_object_data = orig_object.data
 
-    updated_object = meta[:object_data]
+    updated_object =
+      if meta[:local] do
+        # If this is a local Update, we don't process it by transmogrifier,
+        # so we use the embedded object as-is.
+        updated_object
+      else
+        meta[:object_data]
+      end
 
     if orig_object_data["type"] in @updatable_object_types do
       %{

test/pleroma/web/common_api_test.exs

@@ -1343,5 +1343,20 @@ test "does not change visibility" do
       assert Visibility.get_visibility(updated_object) == "private"
       assert Visibility.get_visibility(updated) == "private"
     end
+
+    test "updates a post with emoji" do
+      [{emoji1, _}, {emoji2, _} | _] = Pleroma.Emoji.get_all()
+
+      user = insert(:user)
+
+      {:ok, activity} =
+        CommonAPI.post(user, %{status: "foo1", spoiler_text: "title 1 :#{emoji1}:"})
+
+      {:ok, updated} = CommonAPI.update(user, activity, %{status: "updated 2 :#{emoji2}:"})
+
+      updated_object = Object.normalize(updated)
+      assert updated_object.data["content"] == "updated 2 :#{emoji2}:"
+      assert %{^emoji2 => _} = updated_object.data["emoji"]
+    end
   end
 end