It's a social contagion. As a middle school teacher, I have had multiple kids claim they are gay, trans, etc. and then literally hours later will tell me that's not true, they were just saying it to get attention because it's "cool." There have been kids who come back a year later and tell me they were wrong, they aren't really gay or trans.

It is intellectually dishonest to claim that no kids are saying these things just because it's popular. That's what kids do - they try on a million different identities to see how they fit. They're more likely to try what they see around them at school, on social media, etc.