In Some of my summer reading (2020), when discussing James Holland’s The Rise of Germany, 1939-1941: The War in the West, Volume One:
…. while Italy was allied with Germany, it was a net liability rather than an asset. The Italians failed in North Africa and the Balkans, and so Germany had to commit substantial forces to bail them out.
Grant Piper makes the same point, arguing that The Real Reason Germany Lost World War II was that Italy was a German ally.