There have been multiple threads and comments in this lemmy, as well as other communist subs that have gone in-depth into the first two, as they are most emphasised by the media, so I'll give the "brief" overview of their refutations.

The situation in Xinjiang is an issue of counter-terrorism. That is not to say that all Uyghurs are terrorists, rather that, due to Xinjiang's proximity to US-destabilised regions, there has been a higher chance of extremist ideology in the area, which has affected some Uyghurs. The evidence of this are reports (that surfaced before the camp allegations arose) of Uyghur militias being trained in Syria, and multiple attacks that include stabbings, car rammings, etc, with casualties in the hundreds. So the response of the government is to open camps, or vocational schools, to provide work training for those who may have been influenced by extremist thought. Note that this is not a blanket repression of Uyghurs or their culture. Evidence of this is abundant. It's just not reported on. Please note that this is not a blanket repression of Muslims either - China has other Muslim minorities, like the Hui, that are completely fine, and if i remember correctly, China have more mosques per capita than the US.

A sidenote that I also find interesting that is usually looked over: Xinjiang contains 20% of China's fossil fuel reserves, has the capacity to produce 10% of China's renewable energy, and serves as an essential gateway to the BRI, a project that has the potential to shift global trade and power dynamics further to Asia. I wonder why the US and the media is so interested in Xinjiang?

With regard to Hong Kong, those colonial apologists got off easy. What happened with Hong Kong was essentially an attempted colour revolution, funded by US money. You really cannot say that China is a proto-fascist state, by 1) trying to have an extradition treaty with Hong Kong, which is technically Chinese territory, and already has such extradition treaties with the likes of the US and the UK, and 2) trying to, y'know, not have a successful separatist movement in a key financial hub, and 3) not actually being responsible for the deaths of anyone in Hong Kong, despite the riots going for over a year. With regard to the national security law, it literally is a law that prohibits sedition or rebellion, a law that exists everywhere else in the world. The max sentence for breaking this law is life imprisonment. As opposed to the benevolent US or Japan, where it is the death penalty. More can be said, so I defer to the other megathreads and source compilations.

The Great Firewall is actually pretty good, ngl. Ideally ofc, censorship shouldn't occur at all, but given China's main geopolitical and ideological rival has a virtual monopoly on information, I understand why it exists. It helps filter out the bullshit propaganda that we get fed here in the West, and helps develop Chinese internet services, like Weibo, to rival US ones, like Facebook. Additionally, you can bypass it pretty easily. Just get a VPN. Chinese citizens know this, and those who are bothered enough, mainly the younger generations, will get one. I have heard that the analogy that the crime of using a VPN to bypass the Firewall is like the crime of jaywalking - pretty much accepted.