"The Destruction of Army Group Centre" [Bagration 1944]
Russia had the advantage after 1943, as Germany was bleeding fighting a two-front war, whereas Russia just had one. That was Germany’s screw up, so one can’t fault Russia for taking advantage of it. Operation Barbarossa sealed Germany’s fate; it just took a couple years to make it irreversible, though the writing was on the wall from the Spring of 1942.
Germany committed the mortal sin of land warfare against the Russians: It pursued the Russian retreat, and tried for a knockout blow. That is simply madness when fighting Russia IN Russia. Western Russia— especially the Ukraine — hated the Muscovite Russians, and if Germany had been smart it would have used that to its advantage, instead of pissing off the Belarussians and Ukrainians by subjugating them and slaughtering them.
In WWII, Germany’s biggest screw-up was invading Russia. I’m glad it did, because it was the beginning of the end for Nazi Germany.