First, it all, I was supposing that cosmetic surgeries weren’t allowed in minors (except for those yk, house burned, skin melted situations).
Secondly, how reasonable the law is depends wholly on the studies that were not explicitly quoted and whether there is a significant percentage of people who undergo these treatments during puberty and then regret it.
And the law explicitly states “this use of puberty blockers for gender non conforming children is experimental and not FDA-approved”. Which is legalese I think for “FDA didn’t make studies checking whether those drugs are effective in treating gender dysphoria”