Did I get this accurately?
Red refers to an item dropping in a event chest, while blue refers to an item dropping in a 2x event.
As far as I know, there has never been an event in Sprite, LOD, Void/Cult, CDepths, and WLab after the release of the new waki.
Furthermore, the Battle Nexus and Mad God Mayhem have never seen a chest or other event (beyond just keys dropping) and thus they don’t really count.