The problem is China's government supports just a monumental level of corruption and graft, and has been doing so by exploiting the "developing nation" growth boone.
But that only works once: its days of 7-8% GDP growth year over year[1] are behind it and not coming back. The CCP government seems somewhat aware of this - the social credit system, internet firewall and various other police state measures seem to be an effort to "pre-oppress" the population once the growth levels off (or flat lines entirely) since the implied social contract of China has always been "tomorrow is better then today" - and that's all going to stop once the graft and corruption eats the much lower GDP growth which a developed nation has.
[1] https://www.statista.com/statistics/263616/gross-domestic-pr...