I think it ultimately boils down the their connection to the CCP, and social media's general capacity to sway opinions which can be influenced by malicious design, along with the data collection concerns.
It's a pretty interesting legal question. I don't want a world where the government can shut down every social media site, but if we got to a point where foreign companies like TikTok just started blatant progranda campaigns I don't think they'd last long here.
Nothing, it's not about what they're doing but who's doing it and why. Americans tend to forget that our individual votes do have global consequences in a way that no one else in the world's votes do. Google and Meta don't care about any message specifically, they care about engagement with their platforms and how that translates into revenue. But TikTok is not a private company like Google or Meta, it's almost certainly controlled by a state actor: the Chinese government.
China cares about engagement only to the degree that it spreads a message that in turn promotes their worldview and political agenda. And the best way to spread their agenda is engaging with Americans because, again, the things we decide on a micro level can have insane global consequences on a macro level that no other country can match. That's not to say China is solely focused on Americans, TikTok is obviously in more than two countries, but it's why the federal government in America is concerned. States tend to hate it when other states influence their citizenry, and America, having much experience fucking with other countries' citizens, is no exception. There's obvious First Amendment concerns, after all, there's nothing immediately illegal about agreeing with China, but that gets balanced against safety and fraud for their influence campaign, for lack of a better word.
So basically, Google and Meta only care about money. When Meta causes a genocide, it's due to reckless disregard but they don't want or really even care about the geopolitical event except to the degree it hurts their bottom line. China doesn't care as much about the money, they care about influencing geopolitics.
There are, I’m sure, within existing laws, a multitude of reasons to ban TikTok, but, unfortunately, we have a legislature that is far too tech illiterate to craft a law that can ban any social media effectively for reasons which comport to existing laws due totech illiteracy in the current legislature.
Sorry congress can't hear you. They're too busy trying to craft a law that gives state attorneys general the power to strip lgbt health information off the internet.