A few minutes ago, Apple permanently blocked the signatures of iOS 13.4. Users can no longer restore and return to iOS 13.4.
This decision has repercussions in particular on the jailbreak, since a potential unlocking of iOS 13.3.1 would now be useless for those who have already updated to iOS 13.4.
Recall that iOS 13.4.1 solves a problem on devices that could no longer participate in FaceTime calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier.
In addition, a problem with the Settings application has been fixed, preventing the choice of Bluetooth in the quick actions menu of the home screen.