False positive nullability warning for generic API that's not nullable aware

csproj:

```xml

net10.0

```

Class1.cs:

```csharp
#nullable enable
namespace ClassLibrary2
{
public class Class1
{
public static void M(T? p, I i)
{
_ = i.M1(p);
_ = i.M2(p);
}
}
}

#nullable disable
public interface I
{
bool M1(T x);

bool M2(object x);
}

```

Produces:

```
Class1.cs(8,22,8,23): warning CS8604: Possible null reference argument for parameter 'x' in 'bool I.M1(T x)'.
```

I'm not expecting the warning because the API is not nullable aware. Note that only M1 is producing warning. M2 is correctly not producing any warnings.