The simple reason why China refuses to support Russia more forcefully on Ukraine:
They are geopolitical rivals. China wants a weakened Russia distracted by conflicts.
Russia regards the countries of Central Asia as their rightful subordinates of the "russian empire". Just like they do with Ukraine.
China needs ressources to feed their evergrowing economy, and China's socialist economy MUST grow forever and as fast as possible, or else it will collapse. (In socialist economies, there must be no unemployment, for ideological reasons.)
China is already taking over Africa, but Africa is getting more nationalistic as of late, and more difficult to control, forcefully trying to go their own independent ways without outside interference. Luckily for China... Russia has offended all of the countries of Central Asia, almost outright telling them that they will be next after Russia is done with Ukraine.
And these countries and their nice ressources are right next to China...
https://www.intellinews.com/kazakhstan-s-pivot-towards-china-265567/
No matter how the international situation changes, we will continue to resolutely support Kazakhstan in protecting its independence, sovereignty, and territorial integrity, Chinese President Xi Jinping told a press conference in Kazakhstans capital, Astana, in September.
This was clearly a message to Russia, in the context of the Ukraine invasion. A similar sentiment was expressed by Kazakhstans President Kassym-Jomart Tokayev at the 77th session of the UN General Assembly in mid-September, when he said: We must rethink the linkages between three primordial principles: the sovereign equality of states, the territorial integrity of states, and peaceful coexistence between states.
An apparent pivot by Kazakhstan, away from Russia and towards China, is the latest evolution in the long and troubled history shared by Astana and Moscow. Relations between the two were made inevitable by geography, as Kazakhstan and Russia share the worlds longest contiguous land border.