Jiska Classen appears to have solved the mystery. Apple quietly rolled out a new feature in iOS 18.1 that reboots a user's iPhone if it has not been unlocked for a certain period of time. The new feature causing police headaches is called "inactivity reboot."

Apple has apparently created a new feature for iOS 18.1 that makes it difficult for brute-force machines to unlock an iPhone.

Apple has quietly added a new security feature to iOS 18.1 that automatically reboots iPhones if they haven't been unlocked for a certain period, which makes it harder for anyone to access the phone's data.