@Rycochet posted this short article from Scientific American debunking "Rapid Onset Gender Dysphoria" https://www.scientificamerican.com/article/evidence-undermines-rapid-onset-gender-dysphoria-claims/

One key observation is that parents often experience the coming-out process as "out of nowhere, my teen said they identify as a different gender" while the kids themselves experience it as "I gradually realised I was trans and a year later I finally plucked up the courage to tell my parents". The parents think, "Something recent must have caused this" because they only see the forest fire, not the months of dry wood and smouldering that leads up to it.