The most toxic communities I know of are the Genshin community, Payday 2, FFXIV and source games communities in general.
It’s been years since I ever played CoD but my experience was that it is basically a racial abuse simulator with an FPS in it.
Nowhere near as bad, but I was shocked how intensely elitist and gatekeeperish Hollow Knight’s community can be. I’d already finished the game when I found the sub on Reddit but damn they are mean to beginners!