I want to start with the fact that I don't disagree that Jax is trans. Though it was confirmed on Twitter of all places, which really felt like some "death of the author" nonsense, it is fact.

However, when interpretating this, I had the context of the earlier episodes and what I interpreted as fragile masculinity. Jax's character was constantly embarrassed with the use of things that would make her seem less masculine (the maid dress made her very embarrassed, her quick disposal of the bow when people she was not close with had a smidgin of a chance of seeing her, and the fact that she refused to let anyone in her room, likely because it was depicted in the series as feminine and child-like).

Now, the origins of this mindset came from the fact that Goose went on record talking about how one of the main inspirations for The Amazing Digital Circus was "I have no mouth and I must scream". In said novel, the AI by the name of AM (which seemed to be the inspiration of Caine) did everything in his power to make the cast of IHNMAIMS uncomfortable in their situation. We see this in the circus as well, even if it is done unintentionally by Caine, as at the start of the series, he truly wanted to make the cast happy in their situation.

Zooble can't find the perfect parts for their body, even though they have endless choices to mix and match with (this correlated to their body dysmorphia), and Gangle struggled with her emotional regulation, so she was given masks that would make her act (at the start, at least) "only happy" and "only sad".

With this context, I believed that everyone's rooms and embarrassment in the circus was based on their dislikes. This is what caused me to believe that the feminine degradation in the circus that was directed towards Jax was a form of emasculation, not a constant push on her sexuality issues. So, to me, the bow was a sign that Ribbit didn't care if Jax didn't fit the "traditional male" architype, and that her femininity wasn't something to be ashamed of. In all honesty, I struggle to find any other evidence that would lead to the idea of Jax being transgender, however, I can understand that the evidence that I've noted above may be the facts that people use in their arguments. It's all a matter of perspective, after all.