I just saw a flash of another user's main page that refreshed into mine.
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.
Unfortunately, I can’t recall the username. It was just enough time for me to understand that something was wrong with the page, and in a moment, it switched to my account.