And what's more fatal is that in March of the second year of the war, the enemy will deploy the Panzer IV F2, which can penetrate the T34 from a long distance. The enemy's armored troops are of high quality, and then their sights are a notch more advanced. Rookie T34 crews are often easily picked off for achievements.
Then in September of the second year, the Tiger tanks come into action.
At first, new tanks have a high rate of mechanical failures, so their combat effectiveness is not so high, but once the flaws are mostly fixed, they become the dominant force on the battlefield.
On Earth, the last Soviet Union won with heavy casualties. But in this timeline, the Prussians are stronger than the Sturmtigers, and these new weapons might lead to the collapse of the front lines, ultimately losing the war.
After all, just like on Earth, this timeline's Prussians have not mobilized nor have they adopted a wartime economy.