DV wrong reference

DV wrong reference.cs

public void ConfigureServices(IServiceCollection services)
{
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

         // This is right
         services.AddSingleton<IProductService, ProductService>();
            
         // this is wrong and DV should fail
         services.AddSingleton<IMyDbContext, MyDbContext>();
}