An encrypted backup is a separate recoverable copy of content protected by encryption, together with a documented way to restore it using the required credentials.
A backup must survive the failure you care about
A copy stored only on the same phone may help with an accidental edit but not with losing the phone. A remote copy can survive device loss, yet still be unusable if its recovery secret exists only on that device. Backup location and credential location should be considered together.
Synchronization and backup are also different. Sync may propagate a deletion or unwanted change. A backup arrangement should explain whether earlier versions remain available and how to restore the intended one. Do not assume every cloud folder provides the history you need.
Test the complete path
Use a non-sensitive sample, create the backup, and follow the documented restore path. Check that filenames and contents match and that you know which credential was required. Keep the working original until the restore is confirmed. A success message for upload alone does not verify recovery.
NullVault's platform distinction
NullVault describes portable encrypted backups for Android and encrypted iCloud backup for iOS. Their recovery credentials, destinations and platform requirements are explained in the encrypted-backup feature. Account-free local use does not mean optional cloud storage has no platform account or service metadata.
The backup checklist helps plan verification. Read cloud sync versus encrypted backup and recovery phrase versus backup before deleting an original or replacing a device.