Yet another....
Allied leaders determine in 1942 for a soonest invasion of NW Europe. Preparatory operations and diversions are started vs Scandinavia, French North Africa, Corsica, Crete, ect... To provide trans Atlantic cargo shipping & amphibious lift, air power & general y supply other major operations are curtailed. The two largest would be a increase of LL to he USSR during 1943, & telling MacArthur no S Pacific offensive in 1943. Postponing increases in logistics support to China. Setting aside the Aleutians offensive for another year. In other words every major increase in logistical effort of OTL for 1943 is postponed in favor of focusing the difference on NW Europe.
This has two effects: 1. it can draw German efforts off to seemingly successful peripheral areas, like Africa. the Arctic or Scandinavian front, and more offensive in the USSR. 2. The Red Army is less offensive capable & while it defeats the German offensives, it does not gain much ground either.
As the West Allied Armies grind across western Europe 1943-45 the Red Army moves at a much slower pace than OTL. Without US tanks, Studebaker trucks, Baldwin locomotives Bombardier rail wagons, ect... ect... ect... the Red Army is not much past Minsk when US operation ECLIPSE takes Berlin & the motorized Polish Army races off to Warsaw. Similarly Allied expeditionary Corps have been sent off to Prague, Budapest, Bucharest, Sofia, ect... to supervise the clean up of German forces in those nations. The Red Army reaches a western boundary somewhere between its January and December 1939 borders.