Ben Thompson of Stratechery looks past the thin veneer of data privacy (which is an issue to an extent, of course) to the real issue with TikTok and the US:
The point, though, is not just censorship, but its inverse: propaganda. TikTok’s algorithm, unmoored from the constraints of your social network or professional content creators, is free to promote whatever videos it likes, without anyone knowing the difference. TikTok could promote a particular candidate or a particular issue in a particular geography, without anyone — except perhaps the candidate, now indebted to a Chinese company — knowing. You may be skeptical this might happen, but again, China has already demonstrated a willingness to censor speech on a platform banned in China; how much of a leap is it to think that a Party committed to ideological dominance will forever leave a route directly into the hearts and minds of millions of Americans untouched?
People bucket TikTok in with the other social media apps and services because it looks like one and is used by young people. And sure, there are social elements to it, but the way it serves up the content is not one of them. In that way, TikTok is almost more akin to Netflix. It’s a service that uses algorithms to show you want you want. Netflix does this to drive subscriber growth (and to keep current subscribers happy). TikTok does this to… well, for now it’s to keep eyeballs on the screen to serve up advertising, it seems. But one could see how this can get nefarious and murky pretty quickly.