There are some comics fans complaining about why Barbara Gordon’s gotten less busty. While this is increasingly universal to a lot of superheroines and may also be dependent on the cartoonist as it may’ve been before, keep in mind that the earliest instance of a genuinely flat-chested Babs is in a Super Best Friends cartoon by Lauren Faust. (Yes that one.) If there’s room for a distinctive buxom type in Power Girl, there should be one (or more) in Babs, Raven and Terra.
The latter two also started out as being more flat-chested if I’m not mistaken. Babs could’ve gotten a breast lift though it can be argued that contrary to her detractors, she’s capable of pulling off the flat-chested look well. (Though it could be me preferring to imagine her as such.) To be fair, I’ve seen pictures of female bodybuilders sans implants with very flat chests and visible muscles with veins.
The way Babs’s portrayed’s no different and may arguably be closer to what most female bodybuilders look like (if they don’t take breast implants) though it could also be attributed to bad drawing skills but even then it’s the case for the latter.