this kind of doesn’t make sense to me. A lot of deku’s “flaws” are simply just differences in the storyline. The dark deku storyline in season 6 was needed and was a journey through deku’s mental health aswell, and it’s not fair to say deku changed because of it. Yes, in hindsight, he did, but he’s still very much the deku he was at the beginning.
Deku is also 14 in contrast to koichi being 20, and deku has 100x the weight on his shoulders than koichi. I think it’s fair for deku to change a lot more than he did.