That article questions the methodology of one study. There have been lots:

https://www.transgendertrend.com/children-change-minds/

As far as I know, every study ever carried out on the topic suggests that the majority of children will grow up to be happy, usually gay, men and women without dysphoria once they've gone through puberty.

And while you might view the Keira Bell case as "evidence" that these drugs and the "affirmation only" approach aren't harmful (we all know the legal system never makes mistakes after all), Keira Bell, who is actually living with the effects of that treatment, would disagree with you.