It always had limits
China's position has always been two faced with Russia as it is with everyone else.
China does 3 times the business with the West than it does Russia so if it was sanctioned it really wouldn't do it any good and as Russia's economy is in the toilet, what is Russia going to pay China with? (which makes the whole pay us in Rubles to Europe monumentally silly)
Whilst China said vague things in support of Russia, special relationship blah, it never actually did anything, in fact loys of State owned businesses and banks have been pulling away from Russia, like withdrawing support for payment methods that Russians used etc
There was a story earlyish in the war that Lavrov went to China cap in hand for something or other and was totally rebuffed, got nothing was the rumour
Pre-war, China was Ukraine's single biggest trading partner. They were trading about $18bil a year with a $2bil trading surplus in China's favour. China was getting Iron Ore, Sunflower Oil and Grain from Ukraine. About 30% of China's grain imports came from Ukraine in 2020-21 in return Ukraine was buying Machinery and Consumer Goods
There's also Russia's support for "breakaway" republics which doesn't really sit well with the One China policy with regards to the likes of Hong Kong / Taiwan and who knows, China might even fancy it's northern lands back off Russia at some point if Russia is suitably weakened.
China will always do what is best for China