Vegapunk has constantly refered to Bonney as a child, and one of the translations of the words he uses literally translates to a child of a specific age (I think it was 12/13, can't remember).
Since Vegapunk knew Bonney growing up, he would know her real age. Also keep in mind Saturn has called her a child as well.
Apparently, this chapter proves that Bonney wasn't born at the time she should have been, so, people are thinking she's either younger than she appears and is Ginny's daughter, or is a clone and younger than she appears.
I think Bonney is a clone made of Ginny and Big Mom's Lineage Factor, since her being Kuma's biological daughter doesn't make sense, as Bonney would be a Buccaneer, when she clearly isn't, as we see her turning into a Buccaneer form using her Distorted Future technique, showing she isn't one now:
Bonney's distorted future form is clearly her becoming a Buccaneer; just like Kuma and Klap, her legs and hips are relatively normal, while her abdomen, upper torso, and arms are all gigantic and comically oversized compared to the lower half of her body.
If Bonney was Kuma's actual child, she would appear like this normally, rather than it being a distorted timeline.