It's important to remember that China before Xi's reforms was pretty much a capitalist hellhole. Corruption, environmental degradation and poverty were rampant, while the high rates of profits in China kept western capitalism on life support. Things have improved from 2010 onward, but even the CPC's official stance is that Deng made some rightist errors. The CPC's ability to improve things and correct past errors doesn't mean that they don't make any errors. And given that the CPC made rightist errors, it is only expected that it would receive criticism from the left.
Furthermore, the CPC itself claims that it is only in the very early stages of building socialism. As a result, there are a lot of similarities with capitalism such as a very high Gini coefficient and long working hours. The western left has correctly learnt from its past struggles that reducing working hours and levels of inequality improves productivity and living standards. They have fought against the bullshit excuses from their ruling class which has argued the necessity of poor working conditions for decades. They do not however realize that China does not have the luxury of setting its own working conditions to whatever it wants. It has until very recently been at the whims of the imperialists, who only invest in countries where they can squeeze profits.
The CPC has also made errors in recent years by becoming more nationalistic and has moved slower on LGBTQ rights than is expected of a socialist country. We cannot even justify these mistakes by appealing to the economy or national defense. These latter mistakes are just pure mistakes.