CA2208 incorrectly issued for C# 14 extension members

[BillWagner]

Describe the bug

Use the nameof expression on the extension parameter in a C# 14 extension member and CA2208 is emited. It shouldn't be.

To Reproduce

Try this code:

public static class ExampleExtensions
{
    extension<T>(IEnumerable<T> sequence)
    {
        public IEnumerable<T> Sample(int frequency, 
            [CallerArgumentExpression(nameof(sequence))] string? message = null)
        {
            if (sequence.Count() < frequency)
                throw new ArgumentException($"Expression doesn't have enough elements: {message}", nameof(sequence));
            int i = 0;
            foreach (T item in sequence)
            {
                if (i++ % frequency == 0)
                    yield return item;
            }
        }
    }
 }

The line that throws a new ArgumentException emits CS2208. The explanation is that sequence isn't a parameter. But it is, even though it's on the extension node.

Exceptions (if any)

Further technical details

I reproduced on the VS 2026 G.A. November release.