Oh my gosh, yes! I've dealt with too many of That Guy over the years: in office & business dealings, in my hobbies, even in church & my circle of friends. It sucks you've been plagued by them recently.
The #Fedi concept is so new to me. It's amazing - connected communities w/ civility guidelines that support & protect each other.
The server I'm on is pretty small. May I share your decision with our Admin so we can start conversation w/ our peeps & set constructive expectations, too?