But as for unresearched hunches...
There's lots of jokes in the trans community about how your stereotypical trans girl is on the autism spectrum, with rainbow-colored hair, and into kink, anime, and programming.
I think there's more of a willingness to challenge societal expectations of us in the neurodiverse community, and many of us feel uncomfortable with expectations placed on us around gender roles and sexuality. So I'm curious how much is a causal relationship, and how much of it is a willingness to reject societal expectations that seem irrational. I value my freedom a lot, and the expectations placed on me when I lived as a boy felt stifling and exhausting.
I can only speak to my personal experiences, and I don't believe in policing peoples' decisions to transition, but I have strong memories from as early as five of wanting to be a girl. I was very sensitive as a child. Typical autism-spectrum stuff like sensitivity to sounds, lights, and pain, but also an intense emotional empathy - I was a huge crybaby until my teens, and never felt like I fit in with guys my age or shared many interests with them. So when I found out that transitioning was an option, I pushed hard for it. It's possible that in today's age of greater gender freedoms I wouldn't have had as much reason to transition. But I just don't identify with the male experience at all, and have no desire to see my body masculinize more and more as I age. Also, I can wear so much more colorful and expressive clothes now :)
I think some people transition because they identify very strongly as the other gender, and others (particularly on the autism spectrum) identify outside of the gender binary, so they transition to better express that identity.