You got it wrong, China does not need to be there.
Let's see, Russia economy is doing A OK. Chinese companies are providing and replacing all those goods and services under embargo. Trade is booming in RMB. So you tell me, who is having the economic problem, Russia has all the energy and food they need. What they don't have are components, and here is where China comes in. We might have not sold any drones, but guess where the chips, motors and composites come from? Even alumina, Russia has the raw materials, but the refined product is now from China. They used to import from Norway.
The war could have been avoided, but Ukriane chose to be a slave state and cannon fodder. In WWII, war was inevitable and we had to defend our homeland. There is a big difference. One is a war which was chosen another was an invasion. Russia can actually run this war indefinitely as long as China is buying oil and selling industrial goods to them.