Post the release of iOS 11.0.2 earlier this week, Apple has stopped signing iOS 10.3.3 and iOS 11. This means that it is no longer possible for iPhone, iPad, and iPod Touch owners to downgrade back to iOS 10.3.3 now.
While iOS 11 does bring with it a number of improvements and features to play around with, users of many older iOS devices have complained about poor battery life and poor performance post the update. Many have even gone back to iOS 10.3.3 on their iPhone or iPad due to this. However, now that Apple has stopped signing iOS 10.3.3 builds, it will no longer be possible for users to downgrade back to it.
Since there was no jailbreak available for iOS 103.3, this move is unlikely to affect users interested in jailbreak.