In terms of daily usage it came first from LGBTQ+ communities. It then gained more mainstream attention when colleges and universities, having to work with the emerging generation where acceptance of different sexualities or identities was more common, began to accommodate this. That was helped along of course by the fact that people who systematically study the constantly changing landscape of language use skew towards researchers in linguistics through colleges and universities. So there were two "vectors" of transfer to that community: from both students and linguists.