iOS 12 is part of a radical and final decision made by the Apple company for all iPhone, iPad, and iPod Touch users a week before the release of iOS 13. More precisely, those from Apple decided to completely block the signing of iOS 12.4, the last vulnerable version to an existing jailbreak solution.
iOS 12.4 had a jailbreak solution while it was still the public version offered by Apple, but iOS 12.4.1 was released very quickly by Apple. This update blocks the vulnerabilities used in the jailbreak solution for iOS 12.4, but the installation of the old version remained active until last night.
Starting last night, iDevice users can no longer install any version of iOS for which a jailbreak can be done with an existing solution. Moreover, this will be the last action taken by Apple regarding iOS 12, all attention being now directed towards iOS 13.
