It's a private company, it's very unlikely for them to outright push government propaganda. They'll probably just censor "political activism" on the platform altogether and someday if government establishes tighter control of the platform they might be forced not to censor some of it, like things that undermine the US government.
Large "private" companies in China are not private as you would think of them in the West. The Chinese government or the CCP will own outright or through holding companies shares in a company. So even at the most benign the government or CCP will have influence in a company's governance. Executives and upper management will always be outwardly enthusiastic about all Chinese government/CCP talking points and decisions.
Due to China's "security" laws security and intelligence agencies have essentially full access to large companies' data. There's no real due process so a "private" company's data is essentially government data. There's also the overt and covert censorship and propaganda imposed by the government.
Company executives serve at the pleasure of the government. Anyone not towing the party line or acting with too much independence will get caught up in "anti-corruption" investigations or just be arrested for crimes they may or may not have actually committed.
Realistically it's better to just assume a priori that a Chinese social media company is pushing propaganda and building dossiers of users. It's certainly safer to assume that.
It takes a lot to produce and push government propaganda. It would require a tech company to essentially turn into a government run news organization if they were to do it. Which kind of defeats the purpose of even having different businesses, rather than all of them being propaganda producing news outlets.
China's already got multiple overt state-run "news" organizations. So it's not like there's some dearth of China-friendly content readily available. Propaganda also isn't necessarily just content produced by some Ministry of Truth. Simply censoring or "discouraging" negative coverage of China/CCP in state influenced media can be/is propaganda.
That's just "official" propaganda. The CCP's various astroturfing brigades are well documented (see "50 cent army" and "internet navy"). They show up in public forums of all stripes.
TikTok doesn't allow discussion of the Tiananmen Square massacre, Falun Gong, Free Tibet, or anything other topics the CCP deems inappropriate. That censorship is propaganda by omission. Content users see being primary algorithmic makes it trivial to add in pro-CCP or just anti-West content into people's feeds.
