Stumbled on someone decrying TikTok "multiplicity kids" on twitter, but not sure how I feel about this thing and there's no wikipedia article which is usually the limit of my research.
On one hand DID and OSDD are real things, though some people say it's a culture specific disorder.
On the other kids having calling themselves "we", claiming to be piloted by Harry Potter characters, real-life serial killer and Minecraft YouTubers seems to silly to not be just good clean fun.
On the third hand is you told someone thirty years ago about gender spectrum, genderfluidity, xenogenders, bi lesbians, autism spectrum, they'll probably think you're insane. Maybe there is a subclinical version of DID, like Asperger's to autism, so to speak? I dunno...
Having weird cringey ideas about your self-identity is part of being a kid. They'll grow out of it. And if they don't, we can just be like "oh whoops my bad" and respect whatever they end up with.
That's my take as well. Some of them are surely just being silly, but all attempts to scold weird kids for cosplaying a serious illness are bound to fail anyway.