Following the release of iOS 14.5.1 last week, Apple has closed the iOS 14.5 system verification channel, which means that if you have installed iOS 14.5.1, you cannot downgrade to iOS 14.5.
Apple usually stops signing software updates for the old version after the new version comes out to encourage users to keep the operating system updated.
iOS 14.5 is a major update that introduces a lot of new features, including unlocking the iPhone with the Apple Watch while wearing a mask. It also adds 5G support for overseas dual SIM cards, new emojis, AirTag support, and more.
iOS 14.5.1 is an update that replaces iOS 14.5. It solves the issue of app tracking transparency, which prevents some users from receiving app notifications. It also includes fixes for two WebKit security vulnerabilities. Apple also closed the verification channel for iOS 14.4.2 last week.