Not aware of any of these, which is nice, but iddqd caught my eye since that's a Doom reference! Overall I always thought the Doom community was pretty positive (at least going by Doomworld forums, and various Doom streamers, as I remember them). I thought surely it must be some misunderstanding! Oh maybe they didn't reply quickly enough to take down some drive-by hate speech, but that was it.
Anyway, holy shit, do not go to that lemmy instance. It's rotten to the core. I'm going to go take a shower and play through Episode 1 to cleanse myself now.
4chan wasn't like that before 2015. Well, except for the racism part. It was leftish/libertarian.
It's also the easiest "social media" platform to game. You don't have to make up a history for each user. You don't have to get upvoted. You don't even really need to make sense.
The Doom fandom will always have the dark shadow of the Columbine High School deaths in its history. So shitty people using Doom to be shitty people isn't that far from the mark. Nothing will ever change that, sorry.