We've been aware for ages now that you can't tell if a 3 year old will turn out to identify as trans. There's no disagreement about this in the science. However, what we also know is that by around the age of 12, or tanner stage 2 of development, the odds of someone who receives a gender dysphoria diagnosis not continuing to have this life-long drops to more like 1-3%. I believe this is not the case if they're put on blockers.