Apple devices running iOS 10 and older, as well as macOS Sierra 10.12.5 and older, will no longer be able to sync Safari bookmarks through iCloud starting December 18, 2024.
Users will not lose existing bookmarks or the ability to create new bookmarks on these devices, but new bookmarks will not sync across devices or be recoverable on iCloud.com.
To continue syncing bookmarks, users can update their devices to iOS 11 or newer and macOS Sierra 10.12.6 or newer. If devices are not compatible with the required operating systems, users are advised to export their bookmarks.
In addition to Safari bookmarks, older devices will also lose the ability to use iCloud Backup after December 18, requiring devices to be updated to iOS 9 or newer for backups.