This is my oldest kid :/ I'm going to use male because despite my feelings about everything I do feel a sense of loyalty to respect it.
There is just nothing about him that would even make anyone think he's male. He wears clothes and jewellery that are feminine. But saying he's trans gives him that typical genz Internet high and I suspect makes it easy to be without the pressure girls face. Doesn't matter if he's got body hair when girls are often made fun of for the same thing, because he's a boy. Doesn't matter if he's bad at makeup, etc because he doesn't need to do it at all now, because he's a boy. Despite never having any sense he was in the wrong body growing up, being very happy with typically girls things/clothes, etc, he decided at 14, he's a boy because (i suspect) being a teenage girl generally sucks.
There has to be a reason SO MANY teenage girls are suddenly deciding they're male with zero prior desire, and I think thats a big part of it.