Ukraine

Allegedly Russia can make about 100 tanks per month, only enough to sustain losses of 3-4 per day.
But they have lost about 8 per day on average, They've already been digging into old storage, that require restoration for a while now. And these reserves are dwindling, It's already obvious that Russia is using fewer tanks than they did last year, and that decline is bound to continue, as they dig into older and more and more useless storage. Russia is already restoring tanks that date back to the early 60's.

They are estimated to have about 1700 tanks now, and about 4000 in storage that need restoration to be functioning. So considering they've lost about 8000, that's not a lot anymore. Despite huge efforts to build and restore tanks, it's estimated they now only have about half of what they had when they started the war, and the average quality is worse. The Russian war capability is declining.

https://www.newsweek.com/russia-firepower-war-losses-casualties-ukraine-1880852

It's interesting IMO that the Russian equipment is declining in capability and quantity despite they've had a war economy for some time now. Compared to WW2, where capability increased dramatically very quickly. Russia has not been able to do the same.