Don't Install iOS 12.1.2 If You're Jailbroken
If you want to jailbreak your device, avoid the iOS 12.1.2 update for now.
Jailbreak developers have released a working iOS 11 jailbreak for older versions of the operating system, but they haven't released anything for newer versions or iOS 12 just yet.
Unfortunately, there's no way to downgrade to any of the updates that work with the iOS 11 jailbreak.
Back in 2018 a researcher was able to successfully jailbreak iOS 11.3, but it's unclear if that jailbreak will be made public.
We've also seen an iOS 12 jailbreak proof of concept, but again, there's no guarantee one arrives for the new operating system right away.
Keep an eye out for new developments as we push into 2019.