I was served this page just now, it appears to be for a moderator or admin as there are some extra tools in the toolbar. After reloading this it went away and I couldn’t make it happen again.
Possibly there are some caching settings that need adjusting? Thinking of the admin team on this tough day with tons of traffic thank you for your hard work.
I saw someone else’s user name in the top corner a couple of time while using lemmy.ml instead of my own instance. I think there’s some hastily configured caching going on, perhaps, where some non static content is being cached and served? Just a guess based on my own experience in similar circumstances.