[1]: https://eirifu.wordpress.com/2023/07/30/lk-99-superconductor...
A lot of them are simply trans and tired of dealing with constant harassment campaigns directed towards their gender identity. Of course they're wary about cooperations with people they don't intimately trust.
Sexual politics is tiring and pointless, honestly. With all the ad hominem bullshit and disingenuous positioning, no one is even trying to resolve it.
The culture around anime profile pictures is that you pick a character that you at least somewhat relate to - or used to in the past and embraced that.
For trans people that's usually a character that is at least in some way gender-bending - like being mistaken for the other sex by other characters or people unfamiliar with the franchise.