If you are already using nullable reference types, you might have noticed that they can help make your code safer. But not automagically... This feature relies heavily on everything called by your code being annotated. Unannotated APIs are a big problem for nullable reference types, as they never produce warnings. Values from such calls show extremely optimistic non-null hints, even though there are no guarantees that these hints are correct. Here's a compiler issue for this problem. For example, if you are using LINQ's FirstOrDefault() method from .NET Core 3.1, the compiler not only allows y