My website has a problem with displaying the favicon in the output. Even though I've practically done all the items from the recommendations https://answers.microsoft.com/en-us/bing/forum/all/what-are-the-requirements-to-display-favicon-on/236d6598-41e2-483c-9950-aae8714d943c I just didn't do the last, fifth one: "5. The website must have a valid sitemap.xml file, and the sitemap should include the URL of the favicon file."
It seems to me it's not the best idea to add a link to the favicon in the sitemap. I'm not sure Google would like this.
But it's quiet there.