Is there any fandom you regret exploring?
HMMMM... not really though Genshin comes close. The issue with genshin is how weird it is. Like, on my multi I have huge swarms of people hard blocked because they go out witch-hunting over shit that doesn't matter. We've also had someone actually have litigation brought against them for stalking/doxxing/harassing someone irl from that rp scene.
My lack of trusting other people, refusing to chase people for attention, shy about talking oocly and being pretty liberal about removing people from my safe space has kept me out of all the toxic weird shit that goes on. Which I think is how people need to be. Being on social media -- even rp -- is about curating your own space to be comfortable.
That being said, I haven't been in a ton of fandoms. Since I'm on the spectrum I tend to become fixated on 1-2 for a very long time. Years usually. But I've been in... Yu Yu Hakusho, Full Metal Alchemist, Star Trek, Dragon Age, SOME marvel/DC, Detroit: Become Human, Star Wars, Harry Potter (one of my originals but also is super stagnant/annoying), Final Fantasy.