Also note that "blocking" it doesn't actually "block" much of anything at all - it stops you from seeing the communities located on that instance, but the users will still appear in posts all across the Fediverse, sending their harassing messages to you, pinging your Notifications every time they reply to you, downvoting your own comments, etc. The instance block function is horribly misnamed.

If you want to avoid this kind of thing, I second that recommendation to try Lemmy.cafe - it is the only Lemmy instance that defederates from the Big 3: hexbear.net, lemmygrad.ml, and Lemmy.ml. The latter one is like 1000x easier to deal with than hexbear, yet still nearly all of the most batshit insane comments I've received on Lemmy after defederating from the other two have come from it - and for similar reasons that they get used to how things work inside their echo chamber, and then behave the same way when they venture outside of it - so I consider having defederated from it too worthwhile overall. Although you will miss out on some content such as !Firefox@lemmy.ml that way.