RSS + media thumbnail with XLinq and I don't know why

why.cs

record Pan(string Style, decimal Price, string ProductUrl, string ThumbnailUrl)
{
    public XElement ToRss(XNamespace mediaNs)
    {
        return new XElement("item",
                    new XElement("title", Style),
                    new XElement("description", $"Buy now for {Price}"),
                    new XElement("link", ProductUrl),
                    new XElement(mediaNs + "thumbnail", new XAttribute("url", ThumbnailUrl))
                );
    }
}

public class why
{
    public void make_an_rss()
    {
        var pans = new List<Pan> { new Pan("Detroit", 30m, "https://onlypans.pizza/buy-detroit", "https://hotpanaction.pizza/detroitpan.png") };

        var mediaNs = XNamespace.Get("http://search.yahoo.com/mrss");

        var doc = new XDocument(new XDeclaration("1.0", "utf-8", "yes"),
                        new XElement("rss", new XAttribute("version", "2.0"), new XAttribute(XNamespace.Xmlns + "media", mediaNs),
                            new XElement("channel", 
                                new XElement("title", "xt0rted's house of deals"),
                                new XElement("link", "https://onlypans.pizza/"),
                                new XElement("description", "Bring the cheese if you please"),
                                new XElement("lastBuildDate", DateTimeOffset.UtcNow.ToString("O")),
                                pans.Select(pan => pan.ToRss(mediaNs))
                        )));

        var rss = doc.ToString(SaveOptions.None);
    }
}