The wee little icon that appears for most websites in Safari tabs when you have Safari > Preferences > Tabs > Show Website Icons in Tabs enabled is called a favicon. These micro-badges can help you identify a site by icon, instead of by tab name or other details.
Sometimes these tab icons and the similar ones in the bookmarks list go missing. You’ll see a generic globe symbol or even something that looks broken. A few years ago, I provided advice to reset the state of favicons, but Apple changed Safari’s storage of these little drawings in the interim.
