China's level of internet control and censorship does seem to rise to the level of mistreatment (in that they control and shape access to information, in ways that further the interests of state propaganda), but denying Chinese companies (and the Chinese government) market access to American consumers in some spheres seems fine. It's never been a two-way street with China, and I think we should be engaging in a bit of protectionism when it comes to allowing or not allowing Chinese companies to operate here.
If the US government were suppressing particular views or discussion of some topics (as the Chinese government does to their own citizens), then I would be alarmed. But that's not what's happening here; if the TikTok ban goes through, US citizens' free speech rights will not be meaningfully impacted, as there are other platforms that can and will carry the same content.
Banning a foreign company from doing business in your country isn't automatically censorship. There's nuance.
(And beyond all this, I do worry about the Chinese government using TikTok as a platform to influence Western citizens' thought, culture, and politics, for their own purposes. If they're not doing it already, I'd be astonished.)