Loons backpack is a Rare Fortnite BackBling. Is Part of the Sunshine And Rainbows set.
This backbling was added at Fortnite Battle Royale on 12 December 2019 (Chapter 2 Season 1 Patch 11.30).
The Set Sunshine And Rainbows contains 20 cosmetic items.
The back bling Loons belongs to Chapter 2 Season 1. It's not yet known how to get the cosmetic Loons.