When the US does it it’s just established practise. When a non-US entity does the same thing, it’s suddenly a matter of national security.

Even as someone with a healthy distrust for the Chinese government, this really is the reason why. If Facebook was Chinese and nothing else changed, the US government would feel the same way.

TikTok is used as a surveillance tool in China but US social media is also used the same way here. I wouldn’t be surprised if Facebook at the very least donated public profile pictures to the FBI for facial recognition purposes.

The US would react the same for almost any other government with exceptions to the Five Eyes, in which case they wouldn’t care, and Russia, in which case it would be fully banned.

Not to claim that the US government and the Chinese government are the same, though. Only more or less from a spying and surveillance perspective.