Just now, loading the page https://lemmy.world, I saw a different user’s main page. The page loaded in light mode (I use dark) with the username of /u/froodloop in the top right. Then a moment later, it refreshed into my expected main page with my username in top right. This went past too quickly to get a screenshot, but it was reminiscent of some of the bugs that were happening in the old websocket code.
I think something like metaright@kbin.social would be more the ticket, but I know that Memmy doesn’t have an option in the inbox for either mentions or messages, just replies, so you might not see it depending on what you use to access Lemmy.