Following the release of iOS 14.4 on January 26, Apple has stopped signing iOS 14.3, the prior version of iOS 14. With the software no longer being signed, it is not possible to downgrade from iOS 14.4 to iOS 14.3 if you've already upgraded.

Apple routinely stops signing older versions of software updates after new releases come out in order to encourage customers to keep their operating systems up to date.

iOS 14.4 introduced some notable security fixes for vulnerabilities that Apple says may have been actively exploited, so if you haven't updated yet, it's a good idea to do so.

The update also brought support for smaller QR codes, a feature for assigning device types to Bluetooth accessories, camera authenticity warnings for iPhone 12 models, and more, with details available in our iOS 14.4 guide.

iOS 14.4 is the current publicly available version of iOS that people can download, but Apple has also seeded an iOS 14.5 beta to developers for testing purposes. iOS 14.5 is one of the biggest updates to ‌iOS 14‌ to date, introducing a feature for unlocking an iPhone when wearing a mask with an Apple Watch, adding Dual-SIM 5G support, introducing compatibility with the latest gaming controllers, and more.

Source: Macrumors