I feel like you can sort of tell how long (or not) someone has existed in fannish spaces by how outraged they get about things like this. Like rings in a tree trunk lol. I've been in so many fandoms. At least one, but often multiple at the same time, since I was a teenager. I've seen just. Everything.
Sex pollen. Mpreg. Incest. Monster fucking. Tentacles. Pairings like Snape/Hermione that would be crazy abusive and illegal if they were real. Wild kinks. The babygirlification of all kinds of villains. So much RPF (the 'I sincerely believe they are secretly a couple' kind and the 'this is fictional but it's fun to imagine they're in love' kind.)
You learn to just scroll past shit you don't like or unfollow people or filter tags. The tldr of fandom is that humans are weird as fuck. And creative, and unhinged, and traumatized, and talented. And amazing. And every single thing that you clutch your pearls about 'well surely someone doesn't want to read/write THAT!' - someone does. Probably lots of people do. And those people are perfectly normal. In their offline lives, they're parents and siblings and they have jobs and friends and they go about their lives and they don't cause any harm. And that's the sticking point. There's this really concerning, frankly highly Evangelical idea that if someone enjoys the wrong kind of fiction, they are obviously a Bad Person. But nothing is that simple, and thought crimes aren't real, and you definitely have some thoughts or ideas that someone else would find fucked up. You don't have to like every kind of fic that exists. I certainly don't. But shaming people for their harmless fantasies about fictional characters is so boring. I saw Goody Proctor enjoying a Toxic Ship! Good for you, I'll alert the pope.