MORE HUMAN THAN HUMAN.

i am not transfem so i cannot speak to that (transfem mutuals feel free to chime in here if you want) but i think what your transmasc friends are describing is a bit more complicated than masculinity itself being demonized

you're young, so i have no idea if this is something that was before your time but when i was a teenager, femininity in transmascs was so demonized that when people would make caricatures of "transtrenders" (i have no idea if this is a word that's still widely used, i haven't seen it in years but essentially it just means someone who is lying about being trans for discourse points) effeminate trans men, and more specifically gay effeminate trans men were virtually always the target

here are a couple examples

trans men are expected to adhere to an extremely rigid version of masculinity and anything that could be perceived as feminine is mocked and used as proof that we are faking it (I'd argue it's the same for trans women but reversed)

but there's a bit of a caveat that i think is what your transmasc friends are picking up on and that is that at the same time, cis people infantilize us and get uncomfortable if we pass too well. i don't think this is masculinity itself being demonized, quite the opposite. i think cis manhood is placed on such a pedestal that the idea of a trans man being identical to a cis man is scary for a lot of cis people (including cis lgb people). we're expected to try to adhere to the strict hypermasculinity they push onto us, but they don't actually really want us to succeed.