There's a huge amount of "forced feminization" pornography out there now, accessible by children at a very young age. As well as "lesbian" pornography designed for the male gaze. It's no wonder some males end up feeling they should be like the characters in the pornography they consume.
It's controversial to say this these days, but old school transwomen such as Anne Lawrence were very open about the sexually-charged nature of their dysphoria. (And she published extensively on this topic.)
On top of that, there are many trans-encouraging echo chambers in the form of online forums, subreddits, and Twitter - ready to help anyone even vaguely curious to "crack their egg", as they say.
Maybe environmental estrogens play some part in this rise, but I suspect it would only be a small piece of the larger puzzle.