Don't be fooled by talk about security or privacy. This is simple Nation State realpolitik. TikTok is a propaganda threat controlled by a non-friendly state to the US. Any other way to look at this is naive.
But if Western people are generally not dumb, are patriotic and think rationally, they won't believe foreign propaganda, and so there is no need to ban TikTok, right?
Not teenagers, TikTok's main target