Are media apps and their data collection policies even under the FCC's purview? This seems like an FTC thing at best.
As far as I can tell, this is just some random commissioner (who also wants to get rid of net neutrality and Section 230) making a political statement, and nothing more. Yes, you should be worried about big companies collecting your data. Yes, you should be worried that the CCP has a direct line to VERY influenceable kids. Both of these are legal; the first amendment guarantees the right to publish propaganda that is potentially bad for national security. If you want to stop propaganda, start investing in education, Congress.
I don't see how TikTok is doing anything out of the ordinary here and why they should be specifically targeted. Everyone is doing the same things they're doing. I get that the US is scared that China is going to replace them as "the superpower". Getting rid of some social media app is not going to change that. We're closing the barn door after the horse has bolted. We lost this battle decades ago, and it's too late to stop it.
I really feel like this is a token stance against China and not a whole lot else. They won't stop buying our soybean exports if we take a hard line against TikTok, whereas they would if we took a hard line stance against stealing American intellectual property or invading Taiwan, which is the problem we're actually worried about. So nothing changes, but when Commissioner Carr runs for some political office (his term is up next year, and I'm guessing Biden isn't going to re-appoint him), he has some token "I did a thing" to point to. (And knowing his political affiliation, "I hurt people that aren't white" is probably a good selling point for his candidacy. Sad that such a thing is true in 2022.)
If someone wants to do something about this, Congress should make some laws. "It's illegal at the federal level to bypass device privacy protections to sell ads." or "It's illegal for a US company to help law enforcement track users." or "We don't import goods from countries that have concentration camps that kill ethnic minorities." This will never happen. Congress loves it when companies bypass device protections to sell ads, and they demand that companies like Apple break the security on their devices to aid law enforcement.
Finally, if the FCC really wanted Apple and Google to delete an app from the app store, I doubt that posting a poorly-researched rant to Twitter would be how they go about doing it. I'd be surprised if Tim and Sundar even read this letter.