Not sure where there’s a good summary of the drama, but it started (I think) back in February with some serious concerns about transphobic moderation on tumblr. Openly trans user predstrogen posted

I hope photomatt dies forever a painful death involving a car covered in hammers that explodes more than a few times and hammers go flying everywhere

and he took it a bit too seriously, including banning them for dubious reasons then looking them up on twitter and listing all their old alt account names to their followers, because he’s totally not a transphobic stalker y’all and this is a reasonable thing to do when you’re worth half a billion.