Q: iCloud Restore preventing syncing

This is the closest Apple article I could find related to your problem:

If you need help restoring your device from an iCloud backup - Apple Support

I'm not exactly sure how to finish/cancel the restore, but (unless someone has a better idea), I would turn off the iPhone, log into iCloud from another device, and try to delete the backup.  Then turn the iPhone back on and see if you can then sync your photo library and backup your phone.

It may be better to contact Apple Support with this issue:

Contact Apple for support and service - Apple Support