I read and write fanfiction pretty often. Not trying to give myself away with too many details since I'm pretty well-known in a small fandom, but I once nope'd out of an otherwise decent series because the author had one of the main characters visit an agender doctor who used they/them pronouns. I wish I could say where this character lives because it would make that idea 10x funnier and even less realistic.

In another, the author had a character who explicitly describes herself as a lesbian in canon date a nonbinary OC.

I was once asked if I could make a background character trans. I did not respond.