It is hard to find good numbers on detrans minors, simply because there are so few minors who transition in the first place. But here's one study showing that the regret rate for gender affirming surgery in general is ~1% https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8099405/

Detransitioners get so much media attention simply because it's good transphobia fodder. All there is to substantiate these claims is anecdotal stories from a handful of individuals. These cases should be investigated of course, everyone has a right to make fully informed decisions about their body and it's problematic if that wasn't possible for some reason. However, it is simply untrue that there's a systemic problem with this at the moment.

Again anecdotally, among the (few) detrans people I know, all of them agree they made their decisions fully informed, and take ownership of their decisions rather than blaming doctors.