iPhone users beware! Back up your data before updating...
Following Apple's update to iCloud terms and conditions, some users have reported that notes saved in the Notes app have disappeared.
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Apple updated its iCloud terms and conditions in September. Following these updated iCloud terms, some iPhone users began reporting that their notes had disappeared. Some iPhone users received a notification stating that they needed to accept the updated terms and conditions to continue using iCloud. Some users who took note of this notification and performed the update found that some of their notes in the Notes app had vanished.
ISSUE IN THE NOTES APP AFTER IPHONE UPDATE
Some users who accepted the new terms reported that their notes had disappeared, and while the source of this issue is not yet known, there is a solution. If your notes have disappeared, you should first select Notes in your iCloud settings and then toggle on the "Sync this iPhone" option. If it is already on, it should be turned off and then turned back on.
iPhone users who followed these steps reported that their notes in the Notes app returned.