They started deploying increasing number of attack helicopters as a substitute for artillery that has been decimated in bigger numbers than usual in the recent battles. So they are either running low on it, or at least can't restore it fast enough that they risk expensive helicopters that they now also started constantly losing.
They're using the attack helicopers against Ukrainian tanks that are probing their Southern front. They've already destroyed several tanks and quite a few Western vehicles. I doubt they're using choppers as a substitute for artillery, it doesn't make sense to do that.
They usually avoid using them because they have very limited supply and can't make new ones fast. Now they are losing one a day at least. That's a lot.
https://www.wsj.com/articles/tattered-and-bandaged-russian-p...