it is possible that increased research, education and acceptance has allowed more trans youth to feel 'safe' in coming out to their families and medical professionals and asking for the life-saving help they need. this alone could certainly account for the increase.
it is also possible that increased societal acceptance, particularly within younger populations, on top of normal teenage sexual curiosity, has allowed young people more freedom to explore the entire LBGTQ spectrum, some of which may reasonably be assumed/observed to be 'cool' right now. some of these individuals revert to norm as they mature - i anecdotally know two young people that would fit this category. i would think these young people are much less likely to receive a formal diagnosis and/or treatment beyond a 'social' transition, as professionals working in this field are probably 1) pretty good at filtering thru the typical adolescent angst/bullshit, and 2) know well just how much animosity they are subjecting themselves and their patients to in today's political climate.
in other words...doctors are almost certainly not making these diagnoses nor prescribing treatment frivolously, on a kid's 'whim'. reasonable, critical-thinking people do not assume this to be the case (and yes I realize therein lies the rub 🙄).
both of the above scenarios can be true. in any case... it's nobody's fucking business other than the individual, their family, and their medical professional.