We’re aware of stability concerns on the iOS 13 beta for Fortnite Mobile. We recommend that players do not use the iOS 13 beta at this time.
— Fortnite (@FortniteGame) July 12, 2019
It’s not uncommon for certain apps and games to run janky on beta operating systems, particularly when it comes to Apple’s iOS betas. The full version of iOS 13 is expected to release this fall. The second public iOS 13 beta dropped earlier this week.
Fortnite’s recent ‘9.30’ update added a new throwable weapon called the Air Strike that rains missiles down onto other players. For the full update notes, follow this link.