Bow being possibly trans is a theory I've seen popping up online. Here's one example:
"Plus, there are hints that Bow may be transgender. I’m a cisgender woman, but when I watched the show (for the second time) with my non-binary partner, who was watching it for the first time, they commented a few times on Bow’s possible transness — especially in the episode “In the Shadows of Mystacor,” when Bow, Glimmer and Adora all go to the hot springs together. Although it would presumably be acceptable for a cisgender teen boy to go shirtless in the springs, Bow wears a top just like Glimmer and Adora. Specifically, the top looks like it could be a binder or something to mask top surgery scars." (Source")
no subject
"Plus, there are hints that Bow may be transgender. I’m a cisgender woman, but when I watched the show (for the second time) with my non-binary partner, who was watching it for the first time, they commented a few times on Bow’s possible transness — especially in the episode “In the Shadows of Mystacor,” when Bow, Glimmer and Adora all go to the hot springs together. Although it would presumably be acceptable for a cisgender teen boy to go shirtless in the springs, Bow wears a top just like Glimmer and Adora. Specifically, the top looks like it could be a binder or something to mask top surgery scars." (Source")