They're only fought one war since the big one, and they blew that one too. They seem to still be fighting the war as though it was WW2 - throw men into a meat grinder and kill everyone you see. don't bother with supply lines just take what's available, pound the hell out of civilians to get them to surrender quickly - and so forth. It's how I might conduct a war if this was 1940 and Ukraine was Lithuania.Also if you believe what you read, Russia has already lost more soldiers in a few months than the US lost in the entire dozen of years we were involved in Vietnam. 93+K killed to ~58K US military killed.
Until the Gulf War, we didn't really have men in our military with a decade of combat experience, unless they were leftover from Vietnam. For lack of a better reason - our combat skill level is deep and the experience is there.
Russia has nearly exhausted all of their experienced men - they're sending green troops in as cannon fodder and sooner or later, the people or the oligarchs running things are going to rebel. They're going to have a coup or something, just so they can save face.