Apple Stops Signing iOS 12.1.2 Firmware to Prohibit Downgrades from iOS 12.1.3
Apple has stopped signing its older iOS firmware, specifically versions 12.1.1 and 12.1.2, to prohibit downgrades from the latest release, iOS 12.1.3, which the company published a couple of weeks ago.
In an expected move, Apple stopped signing the iOS 12.1.1 and iOS 12.1.2 firmware for supported iPhone, iPad, and iPod touch devices. This means that as of February 5th, 2019, you will no longer be able to downgrade your devices upgraded to the latest iOS 12.1.3 firmware via iTunes or any other method.
While this has a major impact on the jailbreaking community, which usually relies on older iOS firmware to successfully jailbreak devices, Apple only tries to limit the spread of older software on its devices in an attempt to keep iPhone and iPad users secure and provide them with the best available software.