Barbarossa 43 may turn out a disaster for the Nazis.
For one, the Russians would have adapted into a modern fighting force (T34Ms, monoplaces, etcetera.)
Second, with the purge over, some of the new Soviet commanders would be a little more confident.
Third, no way Hitler can keep a full war footing after a year of peace. The Nazis had trouble selling the war and its sacrifices to begin with, what sold it to the German people is that it was a battle for their very survival. If Germany knocks Britain out of the war by 42, it would be hard to justify totler krieg between Summer 42 to Summer 43.
Fourth, German tank designs, though good and improving by 43, would be somewhat underpowered and stunted without hard lessons learned in Russia in 41.
However, with butterflies, the preceding may not turn out to be the case. Due to butterflies, Britain may have left the war due to an ATL bombing of Baku and disasters in North Africa. Let's pretend they fight on to December 42. The Germans would not immediately demobilize in a few months, so this may provide a window for Hitler to press his political advantage for another foreign adventure. Russia, with even more men on the OTL 41 border with Germany and its allies, may be foolish enough not to have adapted doctrine--while the Germans thanks to lessons in France do have improved Panzer divisions and at this point have decommissioned their Panzers Is and IIs (replaced by mostly 50mm Panzer III3 and IVs, though some long barrel 75mm Panzer IVs would be out due to experiences against Matildas and formidable French armor.) The Italian contribution may be more significant, and maybe with more butterflies German licenses to build Panzer IVs may help Hungary and Romania update a bit ATL.
If Rommel pulled a rabbit out of his butt and captured
the British supply dump on Nov 24, 1941 by sheer luck, perhaps German planning for Barbarossa 43 is a little more in keeping with the lessons of France and Africa--out flanking the enemy and winning via encirclements. IOTL,
a double envelopment of Ukraine was removed in the early phases of Barbarossa's planning. Have von Rudenstedt maintain the plan for double envelopment, and have Rommel fighting in the Baltic states (where in OTL von Leeb failed to take initiative at several crucial times), and we may see (with luck and Russian incompetence) the flower of the Russian army defeated in the field on all fronts--it is not impossible.
As we can see, however, the Russians winning takes little luck, while the Germans winning takes gross incompetence and overperformance. Neither are impossible, but the former is more likely.