Baltic light cruisers were structurally mismatched to Norway

Why did German light cruisers flex so badly in North Atlantic service?

They were lightly built under early treaty constraints and designed for Baltic rather than North Atlantic sea conditions.

The problem came from both regulation and the intended operating area. Early ships were shaped by a nominal 6,000-ton Versailles limit and retained light structural standards even after Germany moved beyond it. Baltic operations did not demand the same hull strength and bracing as the waters off Norway. Carefully balanced weight distribution also became less satisfactory as fuel and stores changed during real service. A design that appears adequate in its home sea can fail when strategy sends it into a harsher theater.