Russia has been actively modernizing, which means getting rid of random wankers off the street and forming armed, equipped, trained battalions, emulating the NATO model.
They progressively redid officer rankings, supply, and maintenance, but clearly fucked up on all levels. This is in the wake of Soviet armaments becoming decrepit and massive corruption, so the downsizing was very important to making their standing army affordable again. Regardless, without tapping the Russian navy, their standing army is only about 300,000 soldiers. Russia isn't dead set on not committing more Russian troops, it is staring down the barrel of instituting a draft for what is still officially "not a war."
The Ukraine invasion has been compared repeatedly to Desert Storm to highlight how hard Russia has fucked up, and how stacked Ukraine is with infantry anti-armor weaponry, but it is also a parallel in that Desert Storm "sold" the idea of the coalition so strongly that it was barely challenged for decades. That one operation went so smoothly and indomitably that it looked like no effort could repel it. This round in Ukraine was supposed to do that, and in 2014 Russia had success with their new tactics, but Ukraine adjusted appropriately over the past years and instead this war is becoming another Chechnya, another Georgia, etc.
No matter if Putin stays in or the oligarchs have him shoot himself in the back of the head and put in a new guy, the Russian army is going to undergo a fifth "modernization" in a few years. Presumably that effort will start with executing whoever has been embezzling the track and tire fund.