Currently, Apple's latest firmware is iOS 12.1.2. If you accidentally update or restore, you'll find yourself on iOS 12.1.2.
Those interested in jailbreaking are typically advised to stay on the lowest firmware possible. Both PanguTeam and Luca Todesco have achieved successful jailbreaks of iOS 12 and the iPhone XS. Unfortunately, there's no word yet about a possible public release.
Pwn20wnd notes that Apple is still signing iOS 12.1 beta 2.
It seems like Apple is still signing iOS 12.1 beta 2. Downgrade to it now if you are on a higher version.
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