Since #1152, the feed logo is preferred over favicons but some sites (e.g. https://rss.golem.de/rss.php?tp=av&feed=RSS2.0) use rectangular site logos (https://www.golem.de/staticrl/images/golem-rss.png) so we should probably only use the logo if it is close to square.

Originally posted by @jtojnar in #1122 (comment)