It was only a matter of time before Apple ceased signing iOS 15.3.1 for all iPhone, iPod touch, and iPad models after the release of iOS 15.4. This means that users will no longer be able to downgrade to iOS 15.3.1 on their devices.
Face ID unlock while wearing a mask, Universal Control for iPads, new emojis, and more were included in iOS 15.4’s March 14 release, along with a host of other new features. The update also includes a new Siri voice for US users, as well as Tap to Pay, which turns the iPhone into a contactless payment terminal for credit and debit cards.
On February 10, Apple released iOS 15.3.1, which included a fix for a vulnerability in WebKit, the engine that powers Safari. The Braille displays may no longer respond to commands after the update was released.
The process of going back to an older version of iOS is frequently used by iPhone jailbreakers. In some cases, reverting an iPhone or iPad back to an earlier version of iOS can be beneficial for users who encounter significant bugs after installing iOS 11.
Although it may have been tempting, the only way to get rid of any serious bugs in iOS 15.3.1 is to wait for a future update instead of going back to iOS 15.3. Anyone who has the iOS 15.4 beta installed can no longer downgrade back to the previous version of iOS.