Perhaps the most important lesson for Putin is the realization that he cannot rely on the military’s assessments of its readiness, forcing him to take a more direct role in overseeing strategic operations. Ultimately, the combination of strategic lessons and a battle-hardened force will make Russia more lethal on future battlefields.
https://en.m.wikipedia.org/wiki/Casualties_of_the_Russo-Ukrainian_War#Total_casualties
It's wild how wide the estimate spread is. From 200k to this absurd 650k.
I guess we'll just have to watch the battlefield to get a better sense of the reality.