Or, and this is gonna sound crazy, I know, it's not because it used to be novel and cool but because young people feel less safe to come out now that the trans panic has done its thing and the current administration has spent an inconceivable amount of money, time and attention painting this marginalised community in a bad light at every perceivable opportunity to do so?

Now do left handedness.

https://www.datawrapper.de/blog/history-of-left-handedness

Did it become trendy? Or did we just stop beating it out of people?

If another kid tells you that they're going to beat the daylights out of you to gain the acceptance of their peers, other kids get the message pretty fast and that message is to conform and to isolate the kid that is going to be the subject of the beating. It has nothing to do with adopting what's cool and rejecting what's cringe, unless you consider the current shift against human rights to be cool and supporting human rights to be cringe.

Trends and beliefs based on culture, real or otherwise, are one thing.

The allegation is grooming: that one group of people is actively persuading another.

I can say that the data you're sharing suggests it's just as likely that the drop in numbers that your site claims started sometime between 2023 and 2024 are due to people becoming more afraid to identify as such due to Republican attempts to restrict LGBT rights and make life miserable for anyone who doesn't identify as straight

>Doesn’t the very rise and fall of trans youth identification contradict your claim?

It does not, no. You cannot be "groomed" into being attracted to a different sex.