Marxism is a science.

The Soviet Union is not a dogmatic blueprint of what is to be done; we learn the lessons from it - good and bad - along with socialism of how it is practised along the ages globally (including Cuba, North Korea, Laos and Vietnam, and attempts at pro-social projects such as Venuzuela, Kerala and Naxalites, and pro-social projects in the Sahel (especially Ibrahim Traore). There are many other historical attempts including Sankara, Cabral, and in Indonesia before the Jakharta Method to name a few.), and then apply it to local material conditions.

We have to consider (1) the USSR fell (2) socialism did not stop at its borders (3) and therefore socialism endured globally including learning from its errors.

One has to understand dialectics, one of the tenets of which is that elements of what is before will be in the synthesis of the new.

If we consider universal healthcare such as the NHS in the UK could be considered a pro-social project under a capitalist country, then in China the "inverse" could be considered where capital is under the power of the proleteriat state.

Like I said Marxism is a science. It is, however, really difficult to do randomised controlled trials for political economies but fortunately we have an almost equivalent in this timeline; India. Compare, what a dictatorship for capital (India) and a dictatorship against capital (China) looks like.

Consider if China is "capitalist" why can't other capitalist countries replicate the speed of progression and development?

How do you explain 800 million people lifted out of poverty? Because if this is not socialism - and you think this is capitalism - then you have to then concede that capitalism is the best system out there. The system that feeds the poor wins.

Assuming one has the intellectual curiousity to want to understand the counter viewpoint from the "enemy's" perspective (for you here it appears to be "Dengism") - ie to be able to make their arguments convincingly - then here is further reading:

(1) Tricontinental Institute: Serve the People - the eradication of extreme poverty

https://thetricontinental.org/studies-1-socialist-construction/

(2) Explaining high external efficacy in authoritarian countries: a comparison of China and Taiwan (a study by liberals doing mental gymnastics when they discover China is more democratic than liberal democracies):

https://www.tandfonline.com/doi/full/10.1080/13510347.2016.1183196

(3) Redsails - Why Marxism

https://redsails.org/why-marxism/

(4) Why the World Needs China by Kyle Ferrana

There are further resources such as critiques on Western Marxism by the likes of Rockhill, Losurdo and Prashad, and lots more articles such as the Why China has Billionaires by Redsails but the above is a good starting point for those lurking and interested.

(Yes this is not a point by point rebuttal debate-bro style, this is an attempt to consider the deeper question on whether China is socialist)