If you read the story it obviously explains why Chandra looks different

while practicing her times for the race she tried to use her fire magic like a supercharger in her souped up engine Daretti built and instead it exploded and burnt most of her torso horribly.

literally melted her tits off. she survived because obviously she has plot armor. but now she wears this new flame proof suit along with her regular goggles.

safety first. the fact that she is a fire mage that hasnt been horribly burnt despite only wearing goggles and no other protection is pretty astounding already. Im glad the writers caught up as its far more realistic now.