Apple stopped signing and distributing iOS 16.5.1 after the release of the iOS 16.6 update on the 1st (local time).
After installing the iOS 16.6 update due to the breaking of the signature, it is no longer possible to restore or downgrade to a previous version of iOS.
Apple regularly stops signing software updates for older versions after a new iOS build is released to encourage users to keep their operating system up to date.
The iOS 16.6 update fixes bugs and security vulnerabilities. Apple plans to release the official version of iOS 17 after the release of the next iPhone 15 series next month.
