Unlike some other commenters below, I don't believe that this is a privacy issue. Instead, I believe that it is a national security issue because TikTok is controllable by the CCP which is ideologically opposed to the United States. The next global conflict will likely be one between the east and the west, with control of information being advantageous to both sides in the conflict. China already blocks the western Internet, so they have an advantage by default.
This position is covered much more eloquently than I put it above in Ben Thompson's "The TikTok War" [1].
This position is covered much more eloquently than I put it above in Ben Thompson's "The TikTok War" [1].
[1] https://stratechery.com/2020/the-tiktok-war/