How Operation Torch temporarily thinned Atlantic convoy escorts

Why did German submarines gain more opportunities when corvettes and sloops were absent from some Atlantic convoys during Operation Torch?

The escorts had been diverted to protect the Torch troop convoys, leaving regular screens thinner and making a temporary operational shift look like general Allied weakness.

Operation Torch required a dense escort around troop convoys sailing from North America and Britain toward North Africa. Moving corvettes and sloops to that commitment left ordinary Atlantic convoys with smaller screens and gave U-boats a temporary opportunity to score more kills. German observers could read that success as evidence that Allied protection was weakening. The missing escorts were actually concentrated around a major amphibious armada, so a local redeployment created a misleading intelligence signal elsewhere.