Cosmic Summer is an Uncommon Fortnite Loading Screen. This cosmetic has been leaked, and the loading screen will hopefully be available to purchase in the near future! Cosmic Summer was first added to the game in Fortnite Chapter 2 Season 7.
How-to Get the Cosmic Summer Loading Screen
Cosmic Summer was leaked or datamined, which means we don't know for sure how it will be released. Most cosmetics that are leaked will be released within 30 - 60 days of their discovery.