Maybe it's because I live on TERF island but I'm still not convinced that milenials are crazy for trans rights over other groups. Eg yougov
Not far off Gen X and boomers really, and boomers more permissive. And us milenials grew up having "boys can play barbie, girls can play trucks" being super drilled into our heads. If there's any truth to it, it's probably down to the everyone is special/participation trophy stuff, but yeah, I'm not really convinced.
I think my generation for a while had a cest la vie attitude right at the start of the explosion of modern trans rights, but that soon dried up when they started to show their true colours and it's been clear for many years now it's not acceptance, it's being held captive to cancellation. So many people i would assume are allies to them are NOT behind closed doors. A lot of people had also never even considered the issue until 10y ago and took the movement at face value for a short time.
Maybe it depends where you live, idk.