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You get more storage on iCloud, and if you don’t have another backup, transferring your phone back will be a little more difficult. It’s not that significant of an issue. When I buy a new phone, I don’t restore from backup using iCloud or Dropbox.
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How to Delete Backup From iCloud on iPhone X/8/7/6 or iPad iOS 12/11 Free Up Storage
You get more storage on iCloud, and if you don’t have another backup, transferring your phone back will be a little more difficult. It’s not that significant of an issue. When I buy a new phone, I don’t restore from backup using iCloud or Dropbox.
If you completely remove your iCloud backup, all of your photographs, communications, and other app data will be lost. Your music files, movies, and applications are not included in iCloud backups. You may access them at any time on your iPhone.
You can’t delete a backup from your iPhone by going to Settings > iCloud and selecting the Delete Backup option. The iPhone’s iCloud backup is updated automatically via an available wifi network while connected to a power source unless the iCloud backup is disabled on the iPhone.