Reason being a new release may come with under the hood issues which have, in the past, affected normal phone use. Restoring your iOS 13 device to firmware released at an earlier date is as common as upgrading to new releases.
Fix iOS Update & Restore Error in iTunes.iTunes Cannot Backup iPhone Under Windows 10.Fix iTunes Won't Update or Restore iPhone.Backup iPhone Files in Recovery/DFU Mode.iPhone Won't Backup to Computer or iTunes.
