CA1859 shouldn't recommend upgrading to an anonymous type

[alexmurari]

Analyzer

Diagnostic ID: CA1859: Use concrete types when possible for improved performance

Analyzer source

SDK: 9.0.101

Describe the bug

When a method's return type is object and the returned value is an anonymous type (new { Name = "Alex" }) the analyzer suggests changing the method's return type from object to <anonymous type: string Name>. Of course, this return type is invalid.

Steps To Reproduce

Console.WriteLine(BuildObject());

private static object BuildObject() // Triggers CA1859
{
    var outputData = new
    {
        Name = "Alex"
    };

    return outputData;
}

Expected behavior

Shouldn't trigger the CA1859 rule.

Actual behavior

Triggers the CA1859 rule.