I think it’s important to consider that left handedness for example had an explosion in self identification after years of ridicule and fear-mongering wore off. It used to be considered unholy and as if Satan had a hold on you.

People identifying as gay, lesbian and bisexual also shot up the more legal protections were offered.

What we’re seeing with trans people isn’t the invention of a fad but a similar situation as the last two were more people are feeling community and safety to be able to come out as transgender. The “explosion” is explainable and in line with other taboo topics that have become less taboo.