That's an interesting question. I don't think there's a consensus on that. I would say they're allies on an ad hoc basis. They're not strategic allies, mainly because China is much more powerful than Russia. That's clear.
However, can a relationship between the two countries cause a lot of problems, in Taiwan or Ukraine? I certainly believe it can.
At the end of the day, I think China is much more useful to Russia than Russia is to China. What worries me more than anything is that neither country really cares about international law or their people's welfare.
I don't think they're strategic allies, but I think the west should do everything it can to prevent them from becoming strategic allies.