Use actor_types() to determine whether the Update is for user

lib/pleroma/web/activity_pub/side_effects.ex

@@ -163,8 +163,9 @@ def handle(%{data: %{"type" => "Update", "object" => updated_object}} = object,
     updated_object_id = updated_object["id"]
 
     with {_, true} <- {:has_id, is_binary(updated_object_id)},
-         {_, user} <- {:user, Pleroma.User.get_by_ap_id(updated_object_id)} do
-      if user do
+         %{"type" => type} <- updated_object,
+         {_, is_user} <- {:is_user, type in Pleroma.Constants.actor_types()} do
+      if is_user do
         handle_update_user(object, meta)
       else
         handle_update_object(object, meta)

test/pleroma/web/activity_pub/side_effects_test.exs

@@ -118,7 +118,10 @@ test "it blocks but does not unfollow if the relevant setting is set", %{
   describe "update users" do
     setup do
       user = insert(:user, local: false)
-      {:ok, update_data, []} = Builder.update(user, %{"id" => user.ap_id, "name" => "new name!"})
+
+      {:ok, update_data, []} =
+        Builder.update(user, %{"id" => user.ap_id, "type" => "Person", "name" => "new name!"})
+
       {:ok, update, _meta} = ActivityPub.persist(update_data, local: true)
 
       %{user: user, update_data: update_data, update: update}