Why did the Red Army continue to suffer massive casualties in 1944/45 even when facing a Wehrmacht that was degraded by years of losses on various fronts and wasn't at its fighting best?
According to Wiki the Soviet Union suffered 6,878,641 total military casualties (including deaths) in 1944. In 1945 it suffered 3,013,507 casualties (not including the Far East). That means in both years they suffered more casualties than the WAllies did for the entire war combined. That's insane.
https://en.wikipedia.org/wiki/World_War_II_casualties_of_the_Soviet_Union
The Soviet Army was badly disrupted by the Great Purge. Then Stalin's insistence that Germany was not going to attack set up the USSR for an enormous sucker punch at that start of BARBAROSSA. The Soviet Army lost millions of men including a lot of the trained cadre. In the desperation fighting of 1941, the Soviets "burned money to keep from freezing"; they threw instructors and technicians into the line as infantry, just to plug holes and block otherwise unopposed advances.
It's arguable that the Soviet Army
never recovered from these losses during the war; that the quality of Soviet Army leadership was, from sergeants to generals, was deficient. Not in bravery or determination, but simply in military expertise, through being vaulted up the command structure faster than they could learn the techniques. Zhukov wrote about this once, though he was mainly referencing the effects of the Great Purge in in a post-Stalin. He wrote that many times, visiting an army or corps or division HQ, he discovered that the commander had neglected something important because he'd never learned about it. At the non-com level - they made sergeants without requiring the necessary training and experience. Many men were promoted beyond their abilities. Some of these grew quickly into their responsibilities; some learned bloody lessons; and some just couldn't cut it.
This happened because at every given moment, they needed more troops quickly. Even in 1944 and 1945, when the situation was less critical, the Soviet Army still didn't have the time to train and promote and evaluate carefully.
This problem had an on-going effect on Soviet planning and tactics. The Soviet Army noticed its quality problems, and adapted by planning operations and adopting tactics that the troops they had could execute - methods which relied on brute force, with comparatively high casualties.
The political system of the USSR also had an effect. Stalin demanded results, and didn't care much about casualties. This ruthlessness carried down into the Army. At all levels, casualty rates that would have checked US or British commanders were accepted in Soviet operations.