Pretty sure they are low on T-72, it has been the work horse for Russian on this war. They only have some 2000 that's serviceable to begin with, all other T-72 they have or had are almost 50 years old. Would have been a big ask to refeb those even in peace time when nobody is sanctioning Russia it would become an impossible task to do
Older T-62 are simpler, those thing can work almost forever as long as you have engine oil in the engine. On the other hand, the simplification means there are not going to be effective in modern battlefield.
Not going to work.
They are doing effective the same thing the Russian did in Donbas after 2014.
The reason why Ukraine did not attack is because they think they will piss off Russia, if they do, but now Russia is already at war, any engineering vehicle can bridge those trench in like 10 seconds, rendering it useless.