@Kooky just provided some data on this point, thanks @Kooky.
As @Kooky mentioned, this is not an easy topic to get stats on. It used to be that a person needed to go thru two years of counseling before they could proceed with transitioning. That's since been relaxed, but I'm not sure that the relaxing was such a good idea. There is a lot of detrans-ing going on, and that's not something that should be ignored.
But that's just it icehorse - you don't actually know that. If your position now is that we just don't have enough data to know how much detransitioning is going on, then we have no rational justification for saying it happens "a lot." All we can say if that's the case is, we don't know.
Now from the data that has been reported above (thank you @Kooky), when data has been collected, the percentage of people who have detransitioned has been consistently low, usually in the single digits. So that's not a basis for saying this happens "a lot" by any reasonable definition of that term.
So it appears that no one can answer your question precisely @Left Coast. That's true with many complex topics. In general we make considered opinions when it comes to dealing with problem areas, even if the science isn't perfect. I can use climate change as an example. I suspect that you're not a climate change denier, even though the science isn't perfect?
So why do you believe in climate change (if you do), but you're so insistent on having perfect data concerning detrans-ing?
I would submit, without derailing the entire thread into a debate about climate change, that we have vastly more data that the climate is changing than we do that detransitioning is some rampant phenomenon.