Not sure about how often it happens after SRS, but I think I read time ago that about 1% or maybe 2% of trans* folks (mtf and ftm people) were changing their gender (legally detransitioning) back to their assigned at birth one. So you would need to extrapolate it to the percentage of all transgenders who are doing not just HRT but GCS too.
I noticed some coinciding facts in all mtf detransition stories I've read about:
- Most transitions started after late twenties.
- They all had therapy, counseling and real life experience before going onto GCS.
- Poor response to T after detransition: dysphoria usually triggered again by T shots, had to decrease their dosages, spread them or even almost halt completely HRT. Some of them even said low E dosages worked better.
- Poor social adjustment: not passing, harassment, very few or no romantic relationships at all, etc.
- Insecurities about ther desired gender perfomance, unrealistic expectations.
- Most still struggling at some degree with gender identity issues after detransitioning.
I think in those cases adjustment difficulties (abuse, insecurity about appearance, social anxiety) bring more distress than dysphoria itself therefore they expected to solve those issues after GCS or even expected GCS to solve them somehow.
If you ask me I would say that a "worst case scenario" should be taken into account before doing most irreversible procedures. Transition sometimes comes at a high price, and it can outweigh dysphoria. It's not always feasible to obtain the ideal result we all want. Furthermore, transition doesn't guarantee happiness, social success nor romantic success. It just can fix some physical issues to a realistic extent.
But after all some would just know after doing all the thing.