After the release of iOS 16.4.1 on April 7, Apple closed the verification channels for the previous iOS version, iOS 16.3.1, making it impossible to downgrade to these versions after upgrading to iOS 16.4.1. To encourage users to keep the operating system updated, Apple typically closes the verification channel for the previous version shortly after the release of the new version.
According to the reports, currently, iPhone users experience the latest version of the iOS update. Apple recently released iOS 16.4.1 along with iPadOS 16.4.1 and macOS 13.3.1. According to the previous report, iOS 16.3.1 was introduced on February 13 that fixes minor bugs including security improvements, and additional Crash Detection optimizations for iPhone 14 models.
Today apple unsigned:
iOS 16.3.1
iPadOS 16.3.1
tvOS 16.3.2
audioOS 16.3.2— Aaron (@aaronp613) April 8, 2023