This is affecting the free speech rights of US citizens directly. You might wish it was as simple as you try to portray it, but it clearly isn’t
Only in the same way that you not letting me into your living room affects my free speech inside of your living room, I think.
This is not affecting US citizens' legal free speech rights. You have the right to say what you want; you don't have the right to say it on a specific platform. You had free speech without TikTok before it existed, and you'll have the same amount of free speech if it does not exist again.