I don't think you need any government conspiracy for this. Tiktok is an inevitable product of the attention economy — moreso a capitalist wart than deliberate sabotage.
They deliberately made SFV educational content only. Tiktok had to comply or face the wrath of the CCP.
SFV about a math theorem or a physics phenomena or explaining how to use a type of conjugation in English? Cool.
SFV thats just a clip of a show or movie with some stupid music overlayed? SFV about a kid doing some stupid dance? Banned.
The problem isn't just the content, though. It's also the medium. SFV as a medium cripples cognition and attention span. It feeds bad habits, emotionally and intellectually.
How many of Gen Z/Alpha have the attention span to sit through a movie, let alone a book? There's even a joke that if someone says they've binged on a Netflix show, it means they're a millennial: younger generations would find that kind of sustained engagement with a subject boring.
SFV is opposed to the kind of engagement you need for deep work.