Russia's estimated to have lost around 30 thousand or so people in this war. You normally have to kill over a 100 thousand to get them to even feel the pinch of a war and have to kill close to half a million before they scream uncle.
Soviet Union had roughly twice the population and much healthier demographics until its last years than Russia does now. So scaling that down 30k is definitely getting into "feeling a pinch" territory as a proportion of military age men.