Core Viewpoint - Apple has officially stopped signing verification for iOS 18.6.1 and earlier versions, preventing users from downgrading to previous system versions after upgrading to iOS 18.6.2 [1] Group 1: System Update Policy - Users who have upgraded to iOS 18.6.2 cannot restore to older firmware through iTunes or Finder due to the closure of the system verification channel [1] - Even attempts to downgrade using third-party tools will fail as devices cannot be activated without verification from Apple servers [1] Group 2: Controversy and Comparison - Apple's forced update strategy has sparked controversy, with supporters arguing it enhances overall security and reduces risks from malware, while critics claim it limits user choice, particularly affecting developers and users with specific needs [1] - In contrast to Apple, Google allows users to downgrade to custom ROMs despite also pushing security updates through mechanisms like Project Mainline, highlighting a fundamental difference in security philosophy and user freedom between the two mobile operating systems [1]