Not are the loads of regretters, we know that from a personal point of view (admitting your mistake and harm caused to yourself), and from a support network point of view (let alone as a victim of the most malicious TRA attacks), coming out as a detransitioner is incredibly difficult. I would argue that not only do we not have any decent stats, if we did have decent stats I would supect they would be 50% to 500% under-representative of the numbers who deep down want to detrans due to these factors.
[The following is pretty speculative, based on my gut feel more than facts...]
And that is before we get onto the idea of when do these people detransition? I believe that broadly speak we might divide trans into old school trans (pre 2000?), new wave (2000-15?) and current cohort (2015-2025?). Old school was tiny and probably bears little relation to the new wave cohort - if we have reliable stats they say nothing about the new wave let alone the current cohort. The new wave is not that large and probably shares things with both the old school and current cohort. The current cohort is much much bigger than the new wave, and if detransition happens 5 to 10 years in, and there are similar numbers each year in the cohort, then half the cohort have not even got to the full 5 years yet, and most of the others have still not done the 10 years that some of them might need before they detrans.
TLDR - I am certain the numbers now are much higher than it looks, and the potential over the next 5 or 10 years for the numbers to skyrocket is surely huge.
And I'm saying all that without really considering the risk of things like strokes as a result of wrong sex hormones. I would not bet on it, but if the stats do start to look really solid and well publicised that men on oestrogen are 5 or 10 times more likely to have a stroke, and AGPs start all knowing at least one TIM in a wheelchair, unable to speak as a result, could that pursuade some of them that detransitioning, medically at least, is the way forward.
The fall-out from this tragedy / fiasco / clownshow will go on for so many decades.