Can’t I use my data to backup my iCloud
Can’t I my data for my iCloud back up
You can only use cellular data for iCloud Backup with iPhones and carriers that support it with 5G. See the following from: Back up iPhone - Apple Support
Note: On models that support 5G, your carrier may give you the option to back up iPhone using your cellular network. Go to Settings > [your name] > iCloud > iCloud Backup, then turn on or off Backup Over Cellular.