For questions about the icons of the sites in the Stack Exchange network and/or the icon attributes as found in the type site as returned by the /sites endpoint
Each site has several icons in several formats. Make sure to include where you found the icon, the exact url and format.
Alternatively when asking about the site type, include which of the url fields are at play:
high_resolution_icon_url got added in the 2.1 version.
If your question is about UI aspects, consider the tag logo as well.