
Idk how to say this without being rude but you're like an inch away from getting my point any media where the top is represented to be more mature, and the bottom to be less mature for no good reason is just not... Like unless there's actually a plot reason behind him being short, it's very weird to make hin child like and make the ml more mature. Like there's good reason behind the ml being mature, but in that case the MC doesn't have to look pre pubescant. That's my point. It doesn't matter what the authors reasons are, if there has to be defense on why he looks like a kid, it ain't valid

Dude, people can be small for all kinds of reasons, especially genetics. The MC is most likely small looking because of the abuse he faces and if you would pay attention to when he's shirtless, he's seems to very clearly be malnourished. The story literally SHOWS why these two are the way they are. The ML is more mature because he's more independent, he has one parent and works while also being in school, which tends to make people more mature than their peers. The MC is abused and kept mainly isolated from too many healthy social interactions, and his parents also didn't have a good relationship, this makes him closed off from others and he lacks emotional development which can stunt maturity. You're making it seem weird and making a problem out of nothing for no reason, c'mon now. Genetics can even play into him looking "prepubescent" as you call it, and there are plenty of REAL LIFE examples of this if you would actually go outside and interact with people.
Twenty eight as in 20 + 8???? Nigga that's a whole 12 year old boy why are we facing the unbelievably twinky bottom apocalypse again guys I thought we as society had already moved past the obsessions with bottoms looking like little boysssaaauuuuhhhh this is the female equivalent of isekai romance I miss when the bottoms looked like.. Adults (it was a trend for like 1 and a half years but whatever)