Apparently there's papers saying they don't impede puberty at all and merely delay it, but as far as I've been aware, we've had a public guinea pig as an example for a long while now: Jazz Jennings. If the blockers were no big deal, then why was the bottom surgery such a problem? If I remember correctly, there was so little tissue down there because their penis never developed into an adult penis that there were multiple issues with the skin being stretched too thin and the sutures kept popping. Truly horrifying.