I'm shit at noticing what instances people are from, but if there is one specific one targeting posts here it might be worth letting the mods know? I also wonder if the deleted comments were deleted by the mod team? Though it wouldn't surprise me if your guess about them deleting for lack of attention is the correct one lol
Either way, I try my best to avoid getting dragged in to "debate" with these people, because there is no good faith and it almost never leads anywhere, but what I will do is call their shit out then block, let them yell in to the void lol