iOS 14.5 brings a lot of updates, including the option to unlock the iPhone through the Apple Watch while wearing a mask, new support for AirTag, and App tracking transparency allows users to control which apps can track their activities in other companies apps and websites.
Apple usually stops verifying the old version of iOS within a few weeks after pushing the official version update. For some users who update to the latest iOS system, when they encounter major bugs, the downgrade method is sometimes very effective.
This is why Apple will wait for a while before closing the verification channel of the old iOS system. The iOS 14.4.2 provides important security updates, and Apple previously recommended that all users install it.