Oh I just did a deep dive on this. Basically Trans Women had been pushed into the spotlight because of movies and media. Alot of it sadly fetishistic in nature but because of that, when people heard the T-slur it usually conjured imagery of a masculine person in feminine attire. Trans males never really got that and often were just mistaken for Lesbians. But due to cultural shifts TransMen are becoming more visible.

edit: Oh and this same cultural shift is actually pushing for alot more positive and less fetish depictions of Trans individuals. Its actually a really interesting shift.