Use username as display name for suspended users or users with blank display names (#25276)

app/serializers/activitypub/actor_serializer.rb

@@ -99,7 +99,7 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
   end
 
   def name
-    object.suspended? ? '' : object.display_name
+    object.suspended? ? object.username : (object.display_name.presence || object.username)
   end
 
   def summary