I've joked that Tik Tok is a Chinese psyop meant to weaken the next generation of the west (it's banned in China itself), but it looks less like a joke all the time.
There maybe be some technical reasons for this.
But feeding into the psyops narrative, it's good practice to separate your intelligence gathering into domestic and international. Ex. CIA and FBI
I'd imagine that for China, US/Western Tik Tok is a literal treasure trove of useful information on the state of practically every facet of US/Western life and culture. Oh the subtle and untraceable mischief you could get up to by just turning a few knobs.