Source on de-transitioning data:
https://transequality.org/sites/default/files/docs/usts/USTS-Full-Report-Dec17.pdf
Now observe how the overwhelming majority of de-transitioning experiences are driven not by a private realization the transitioning was wrong for the person, but by experiences of transphobia and trans-antagonism.
This is also true more broadly of mental health struggles for trans people. They are overwhelmingly the product of trans-antagonistic experiences, transphobic rhetoric, and a lack of gender affirming care. Gender affirming care, in both the technical (medical and mental health) sense as well as the social support since, is almost always the most effective way to improve mental well-being for the community.
And on broader patterns of mental health outcomes for transgender groups:
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2789423