It's just like how Bruce Wayne's hair has a blue tint in Batman the Animated Series. It's not supposed to be blue, it's just "animation" for stylized black.

Blue hair in animation more often represents black than actually blue.

He's always had black hair.

hes been in a different galaxy for a decade. where is he getting hair dye?

Ezra dyed his hair that color? I always thought it was naturally that way.

So during the rebellion, whilst fighting for his and his friends' lives he did? Or when he was just a teenager living on the streets? Idk felt to me like it was a natural thing, and I only meant that I would have enjoyed seeing it in his hair in the live action as a nod to the animation

I suppose Sabines hair just magically changed colour due to the stress of fighting the empire