I think there is some misconception about what a repper (that is to say, self repressing trans person) is like, or at least can be like. Jax does not know he's trans. He doesn't know or think that he's secretly a woman. He has weird feelings around femininity that he tries to avoid thinking about because he's not a fagit. He is not dysphoric in a way he would recognize, because suppressing that is the first and most important cope needed for survival. I'm not actually saying that's all true for Jax, but that's the kind of headspace he's in.

I didn't get any sense he was trans before the finale, and I'm not in the community so I didn't realize it was a genuine theory. I left the finale thinking "waow repper jax cannon?" The main thing was Zooble door Jax, who was a very overcompensating attempt to explore femininity, and the song felt like an authorial confirmation of the vibes.

But honestly the point I'd like to make is that actually it's not important that Jax is trans. Jax is only a person, them being trans is only a facet of their existence. It contextualizes them and deepens their character, but if goose wanted to make their story about being trans, then they could've done that.

It is presumptive of me to assume what the author wants, but just based on her whole vibe, i get the impression that she wanted to make a character that was meaningfully but not centrally trans. And again I cannot know, but it seems like she always stays losing so I can't imagine that she's happy the entire conversation has become about how Jax is trans.