Putin expected / hoped that China would pledge to support him militarily in addition to increasing economic and political support. What he fails - or refuses - to see is that it doesn’t really benefit China for Russia to “win”. It wouldn’t be a net negative for them, per se, but ultimately it doesn’t benefit Xi if Putin manages to capture <random Ukrainian city>. What DOES benefit him is for Putin to become more and more dependent on China as their only major trading partner and access to the outside world. The longer Russia is engaged in a fight in Ukraine, the more one-sided the power balance in the relationship becomes. Not to mention that it keeps NATO’s eyes on the west rather than the east. Xi certainly is not going to risk western sanctions and his own military readiness by depleting his stocks of munitions so that Putin can realize his fantasy of rebuilding the USSR.
From a strategic perspective, the best thing russia could do for themselves is retreat from Ukraine NOW, turn over war criminals, and begin the (multi-decade) process of trying to repair ties with Europe. Because China is not going to treat them well.