Because there are always minor updates after the major ones.
Apple on Monday released iOS 14.5.1 and iPadOS 14.5.1, which function as minor security updates that arrive just one week after the release of Apple’s iOS 14.5 and iPadOS 14.5 updates. There are also companion updates in the form of the watchOS 7.4.1 update, and an iOS 12.5.3 update for older iPhone and iPad devices that don’t support Apple’s latest operating system versions.
Per Apple’s release notes, the update fixes a bug with the App Tracking Transparency feature that may have prevented some users from receiving prompts from apps:
This update fixes an issue with App Tracking Transparency where some users who previously disabled Allow Apps to Request to Track in Settings may not receive prompts from apps after re-enabling it. This update also provides important security updates and is recommended for all users.
The iOS and iPadOS 14.5.1 updates can be downloaded for free and the software is available on all eligible devices over-the-air in the Settings app. To access the new software, go to Settings > General > Software Update.
If you’ve tried the updates, please let us know about your experience in the comments.
Via MacRumors