Just as the USA viewed the war in Ukraine as a cheap way to degrade Russian military capability at essentially no cost to the USA, so too does China view the same conflict in the same way: as a way to deplete US capability at no cost to China. The problem with this perspective is that it's actually extremely stupid. The USA failed to grasp that the conflict in Ukraine is actually existential for the West, and China fails to grasp that involvement in the conflict will create problems for China far beyond its gains (basically turning Russia into a Chinese client state) that include the increased likelihood of the US moving toward rearming at a rate China will not be able to match over the medium term. The collapse of global trade will hurt China more than it hurts the USA, and ultimately if an economy is ailing it can't afford to spend as much on its military. Just look at Brexit-crippled Britain, that no longer has a functional military and certainly can't afford to rebuild one.