Tik Tok is the reason I've been told several times I have ADHD. Pretty sure I don't! This phenomenon is so infuriating. The only half-convincing defense I've heard of it is that it could, maybe, theoretically, disseminate information about illnesses to people who don't have the money to see a professional, but the other effects are so much worse it doesn't seem worth it.
Tiktok and pop-culture generally make me very skeptical on "ADHD", the so-called "spectrum" and "neurodivergence" generally. I'm not saying these things don't exist, but much of it seems very difficult to falsify -- which needs to be the gold standard of determining these sort of things; e.g. "By what process can someone reasonably determine that they are NOT neurodivergent?"
So the issue isn't so much falsifiability per see but instead the whether you trust the judgement of people who decide what is "normal" or "not normal".