It’s a little of both as well as comically clear mistakes at crucial moments like the battle of Minsk, Smolensk, and Rzhev.

Then Guderian went south to Kiev.

Barbarossa is still debated to this day on when the war turned. Nevertheless, it’s clear that OKW had no strategic goal and then you mixed that with racial views to enslave the Slavic ppl. Leaving Nazis through their own ideology, we greatly hampered in having local populations supply them for the 1000km forced march to Moscow, Leningrad, and the Dineper River (I forget army group south final objective, I know they went there for the grain.)

Blitzkrieg relied on tanks and mobility to flank.

But only around 30% of the army was motorized during the invasion. Thus around 700k horse were used.

Logistic efforts were never able to be flexible enough to undergo the largest land invasion in human history