Most smartphones are made in China, so CCP has access to them at the hardware level. My bet is that tiktok has hacked the human psychology: it's an equivalent of addictive sugary drink spiced with coke; it's a problem by itself, but it's a much bigger problem once we realise who manipulates the us citizens. I see tiktok as a backdoor into democracy: it can sway opinions of the masses or it can run social experiments.