Blizzard sent out the following

Players have asked us time and time again for this feature… and now Double XP is back!

Jump into Overwatch today to earn double XP from June 6 – 10th.
https://twitter.com/playoverwatch/status/1136694245249540096

This is your last chance to join the Overwatch Anniversary and earn new skins, dances, sprays and more. The event features all past seasonal cosmetic items, as well as most of the past seasonal brawl including those found in Overwatch Archives – Storm Rising. Overwatch Anniversary ends on June 10th.