https://wccftech.com/ios-12-beta-users-seeing-false-update-prompts-heres-how-to-fix-it/

Many iOS 12 beta users have been seeing false update prompts on their iOS devices. The message on the device informs users that a new iOS update is available and that they should update from the iOS 12 beta. However, what’s peculiar is that there are no new updates available. While there is no update available, it is reported that the prompts are appearing due to a bug in iOS 12 beta 11. Let’s dive in to see some more details on the matter.

The prompts appear because of a bug in iOS 12 beta 11 according to 9to5mac’s Gui Rambo. The bug appears as it presumes the expiration date of the update is nearing. The prompts appeared after Apple rolled out its iOS 12 beta 11 updates but they became more frequent since yesterday. The prompt is quite annoying for all iOS 12 beta users and appears everytime you unlock your iPhone or iPad.