It does feel like that but when I read it back, the sex scenes built is honestly the same imo. He is broad shouldered but have a tiny waist. His hair being down in the imaginary one doesn't help either making him look younder with the baby face.
In terms of built he seem the same, but I think what threw us off is the size difference between them. The first chapter barely shows how big the seme actually is compared to him.. I guess that's why he seem smaller now

I swear the bottom used to be way bulkier, I went back to the first chapter and they where both bigger