Hello ! As a big fan of Arena Swarm, I just found this in the settings while in game, hotkeys for Swarm Arena, deployed since last patch, I don't know anything about this, if the gamemode is coming back, but I'm sharing it with you.
While wrinting this text, the settings are still available, in custom game, practice tool or even ranked or draft.
Hey all, unfortunately this doesn't mean Swarm is coming back anytime soon - these showing up is unintentional. If/when Swarm makes a return we'll be sure to give you all a proper heads up