I don't use TikTok, so I'm probably wrong here.. but isn't TikTok "algorithmically served user generated content" rather than "community" or "social media". As I understand it, it's like a TV station. If there's "dialog", it's in the form of answer-films, rather than actual discussion. If it does behave the way I think it does, then it backs up the idea that social media is on the wane.
TikTok can be considered at least 3rd generation, if FB and Twitter were second and first is MySpace. I am sure one could argue there are more generations. Twitter is not among the first social media god generation.
In my experience, first generation happened on BBSs (contemporaneous with usenet, which wasn't on my radar until it was nearly dead). Then came niche community discussion boards and AOL. Then, Geocities and webrings. Friendster came out a few months earlier than MySpace, but they were close enough to be the same generation. By my count, TikTok is sixth generation? I can't help but feel that I'm missing a few; not even considering my anglocentric experience.
Between this and Facebook's recent woes, I wish this was a sign of a global tiring of social media in general.
I'm frequently wrong about these things, but one can hope.