https://www.gamespot.com/articles/fortnites-new-update-adds-spiky-stadium-port-a-for/1100-6461829/

Epic Games continues to expand Fortnite: Battle Royale with new updates every week, and the latest patch is no different. Update 4.51 adds the Spiky Stadium to the Playground mode, along with a new Port-a-Fortress item for all Battle Royale variants. In addition, a new LTM has been introduced: Soaring Solos. Meanwhile, the mysterious cube has plunged to its doom, turning Loot Lake purple.

Spiky Stadium is a deployable arena found in red Supply Drops in Playground only. It contains Bouncers and Damage Traps, and Epic says the item is designed to promote creativity amongst the community as it thinks up new activities.