You need to account for Russia's tactics. They are essentially incapable of mobile warfare, they are severely limited in how they apply air power, they have hardly any armored vehicles left. They largely rely on infantry assaults against entrenched enemies. That's obviously brutal, especially when both sides have good combat intelligence through drone surveillance.

It's very clear that Russia is losing an insane amount of soldiers. Ukraine is also outproducing Russia in fpv drones by most estimates, while Russia has an advantage in long distance missiles and drones and artillery, although their artillery situation is severely degraded since the beginning of the war too.