Oh. I subscribed to this post because I hoped someone would be able to give an answer too.
It’s been a day, so before I forget and on the basis that some answer is better than none at all, I’ll have a crack:
400 Bad Request isn’t much to worry about, it doesn’t mean anything is malfunctioning and it can happen for a gazillion reasons. One is you’ve joined a new community and someone Likes a comment you don’t have (particularly if it’s nested in other comments you also don’t have). Another is if someone Likes a post or comment by a user on an instance that you’ve defederated from (your instance is defed’d from lemmygrad and hexbear whereas lemmy.ml isn’t)
As for 499, that seems to be a client issue, and that client mostly seems to be beehaw, who are stuck on an old Lemmy version and being increasingly wonky (in the other direction, they often reply in HTML rather than JSON and randomly decide that their communities’ inboxes don’t exist, so I wouldn’t worry about stuff from them either)
Fuckin’ hell, is it Monday again already? Suppose it is, technically. Anyway, still listening to In Waves by Jamie XX. I’ve tried listening to other stuff, but I’m finding them all fatally flawed by not being In Waves by Jamie XX. The last track, a distinctly Irish reversioning of Carl Sagan’s Pale Blue Dot, continues to amuse me.