The percentage of specifically children who would grow out of it is way, way higher than 30%. I don't have the numbers at hand, but I recall it was something like 80% of prepubescent children who think they are trans realize they aren't if they're allowed to go through puberty normally and un-groomed. Essentially it's children who don't have a lot of their sexual characteristics yet being told that feeling like they don't have those characteristics must mean they're trans, rather than just meaning that they're prepubescent.
The percentage of specifically children who would grow out of it is way, way higher than 30%. I don't have the numbers at hand, but I recall it was something like 80% of prepubescent children who think they are trans realize they aren't if they're allowed to go through puberty normally and un-groomed. Essentially it's children who don't have a lot of their sexual characteristics yet being told that feeling like they don't have those characteristics must mean they're trans, rather than just meaning that they're prepubescent.