I encountered the same problem today. After some investigation I found out that C# and C# Dev Kit extensions are not the ones to blame (they haven't been updated for months already), but it is the .NET Install Tool extension - that is automatically installed by C# or C# Dev Kit.

.NET Install Tool got updated yesterday and that broke the debugging of my app. No wonder once you take a look at its description:
This extension installs and manages different versions of the .NET SDK and Runtime.

Once I downgraded the .NET Install Tool I could debug again.