1. Government surveillance of domestic citizens is far more intrusive than in any Western country. (NSA revelations are not a refutation).
2. Prominent citizens get disappeared. There is little to no transparency in the judicial process.
3. There is no freedom of speech in China. You cannot criticize the government from within the borders effectively without being in danger.
4. China does not have a free Internet in the sense any Western country does.
5. Social credit scores exist, and will be used to reinforce the government's authority.
6. There are ongoing human rights abuses in China other than what I've already mentioned.
You can evade this all you want and talk about how nobody can possibly know about China unless they go there. But you can't refute any of these, so that is all you can do.