Null suppression does not work when Assert is fully qualified

[RenderMichael]

The following code has a null warning on M(x)

using NUnit.Framework;

class C
{
    [Test]
    public void T()
    {
        object? x = null;
        NUnit.Framework.Assert.That(x, Is.Not.Null);
        M(x);
    }

    void M(object o)
    {
    }
}

The following code does not

using NUnit.Framework;

class C
{
    [Test]
    public void T()
    {
        object? x = null;
        Assert.That(x, Is.Not.Null);
        M(x);
    }

    void M(object o)
    {
    }
}