China isn't going to lift a finger to save Russia - a broken Russia is even better for them because they would be utterly dependent on China and China could just bend them over and have their way with them.
Prior to this, I am sure they were looking at Russia to help them out against the West, but given how badly Russia has performed, how they have wrecked their armed forces in the process and can't replace their lost vehicles because of sanctions on critical components, they'd be of very little help to China in the event of anything happening. No doubt China realises that they would in effect be on their own.
And Taiwan has been watching Ukraine's heroic resistance with interest as well. They are learning the lessons from it. China is probably not happy about that either.