China is happy as a clam that Russia is self-isolating and destroying their internal economy. The natural resources of Russia are vast and if China is the only one exploiting them and funneling them into the Chinese economy it'd be an excellent outcome. I don't think China is opposed to strong economies as trade partners but dependent economies are much easier to control and monopolize.

Russia is only isolated from the west (e.g. exports to India are booming) and its internal economy is growing faster than Europe's.

Russia holds leverage over China because China is incredibly resource dependent and very susceptible to the threat of blockade through the first island chain by the US. Only Russia can bypass such a blockade with fertilizer, grain, oil and gas.

The US is driving these countries into each other's arms.