Friends, we're making awesome progress adding and revising icons in MediaWiki to enhance usability of the site on desktop and mobile. What we're not doing is a great job of avoiding replicating work. I can think of several instances where we're using very similar but slightly different icons to represent the same concepts. Let's use this bug to track down that wasted duplicate effort, and standardize on one icon for each concept, where we can.
T55875: Notification icons are not ready for high-density displays (use SVG instead of PNG where supported)