This is related to this post, but I still see this issue pop up fairly regularly. As far as I can tell it's a bug in the latest version of Lemmy, so we might just have to "deal with it" for now.
This only affects the desktop experience - accessing the instance through the API via an app works perfectly fine.
I'm going to leave this up for the time being so hopefully people understand that when the site "goes down", it's not really down. Thanks for understanding, everyone!