Cannot serialize XML with nested classes (2) - Microsoft.XmlSerializer.Generator 2.2.0

[NUnitTester]

The problems ocure while transforming a project from .NET Framework to .NET Core 3.1 with
Microsoft.XmlSerializer.Generator 2.2.0.
It seems to be a bug in the generator. There should be no reason to analyze types that are not serialzed.

The following example works fine with .NET Frameworks but fails in .NET Core.

    [Serializable]
    [XmlRoot("Info", Namespace = "N1")]
    public class Info1
    {
        [Flags]
        public enum Flag : uint
        {
            F1 = 1,
            F2 = 2,
            All = 3,
        }

        [XmlAttribute("flags")] 
        public Flag F { get; set; }
    }

    [Serializable]
    [XmlRoot("Info", Namespace = "N2")]
    public class Info2
    {
        [Flags]
        public enum Flag : uint
        {
            F1 = 1,
            F2 = 2,
            All = 3,
        }

        [XmlAttribute("flags")] 
        public Flag F { get; set; }
    }

Error Message:
There was an error reflecting type 'DbGenerator.Info2.Flag'.
Types 'DbGenerator.Info2.Flag' and 'DbGenerator.Info1.Flag' both use the XML type name, 'Flag', from namespace ''. Use XML attributes to specify a unique XML name and/or namespace for the type.

Should not they have the same namespace as outdie the class including it? N1 or N2?

[HongGit]

same issue as #36921 and same workaround