Just over 24 hours after releasing iOS 12.1.2, Apple has gone ahead and stopped signing iOS 12.1. This means that it is no longer possible for users to downgrade back to iOS 12.1 from iOS 12.1.2 iOS 12.1.1 if one has not saved the necessary SHSH.
Normal users will not look to downgrade back to iOS 12.1 but if you are interested in jailbreaking your iPhone or iPad, it is highly recommended that you stick to iOS 12.1. This is because iOS 12.1.1 comes with a number of bug fixes and security improvements which will likely hinder the development of a jailbreak for it.
If your iPhone or iPad is running iOS 12.1, you now might want to be careful about not upgrading to iOS 12.1.1 – iOS 12.1.2 since all gates of a possible downgrade back to iOS 12 are now closed.