Ethics and lasting harm, up to and resulting in an actual suicide ten years later.
These “transgender” adolescents can only be transformed from a male into a neuter, or a female into a neuter. No successful full transformation of a male into a female, or a female into a male, has ever been done in the annals of medicine, and it never shall be. There is no way to change the chromosome pairs XY into XX, short of perhaps divine intervention, and I do not believe that is a plan of of any deity in known human religions.
Even the insane Dr. Mengele didn’t try this.