There are cases like https://github.com/dotnet/runtime/blob/main/src/mono/System.Private.CoreLib/src/System/Reflection/RuntimeAssembly.cs#L255 where APIs which is not supported in single-file setup are not issuing any warnings when used. What is also strange is that the APIs which are annotated but have override don't need the annotation either, for example, https://github.com/dotnet/runtime/blob/main/src/mono/System.Private.CoreLib/src/System/Reflection/RuntimeAssembly.cs#L77