I see your instance is federated with both Hexbear and Lemmygrad. Going to gesture vaguely at that being the root of your problem (or at least > 90% of it).
Blocking instances helps, but you'll still see users from there in the comments and in other communities (not on the blocked instance). Some UIs will hide users from blocked instances. I know Tesseract does (I wrote it to do that), but others might as well.
My experience here has been pretty great after getting my blocklist and feed curated.