I was bored saw many comments about how Jax being trans "came out of nowhere", so I wanted to make this post proving the opposite.
During the bar scene Jax laughs and makes a comment about Zooble being a tattoo artist and a bartender, two queer stereotyped jobs. Thing is, this is pretty insider knowledge since these stereotypes are not as widely known in mainstream cis-het spaces.
When Jax called his tail as the 'pinnacle of masculinity', he finds out it's missing.
And more importantly, there's the Jax maid scene.
First he acted infurated, but as he shifted attention to other stuff, he acted quite comfortable in it.
There's the fact that while Evil Ragatha told Ragatha nobody loved her, Evil Jax told Jax he looked good in the maid outfit, being a possible reflection of his internal and repressed thoughts.
Jax, when pushed by Pomni, says "you think I'm a misunderstood chicken fetus in an egg that is waiting to be cracked open!", and for those who don't know, egg is trans slang for someone who is trans but is not conscious about it, and cracking open is realizing it.
Jax is the only who didn't want to wear a swimsuit and expose his body, something common in people with dysphoria
He also talked about Zooble's ability to change their own body with a grain of envy.
One of the most explicit details is Jax's room, which looks like that of a small girl, and since apparently the characters can't design their rooms, it could be based on Jax's mind.
There's the song "isn't she lovely?", which talks about the birth of a woman, with Jax moments playing at the same time. Really explicit.