The beta versions of iOS (and iPadOS in this case) are operating system versions that may still contain bugs and are not fully polished. Apple distributes them to developers so they can test their apps in the future version and report the bugs they find. Generally Apple does not allow downgrade (back to a previous version of the operating system, the opposite of upgrading), but being a trial version is possible.
Steps to return to iOS 12 from iOS 13 or iPadOS
If you want to return to iOS 12 from an iPhone or iPad with iOS 13 or iPadOS respectively, follow these steps:
Step 1. Download the latest version of iOS 12 available for your iPhone or iPad to your computer in IPSW format (don’t worry, even if it’s not from the Apple website, check that it’s an unmodified version before installing it).
Step 2. Make sure your Mac or PC has the latest version of iTunes available so you won’t have any problems installing iOS 12.
Step 3. Turn off Find My iPhone in Settings > iCloud > Find My iPhone (even if it’s an iPad).
Step 4. Connect your iPhone or iPad with iOS 13/iPadOS to your computer using a USB cable.
Step 5. Put iPhone/iPad in recovery mode (DFU).
Step 6. Once iTunes detects the device in DFU mode press Alt/Option + ‘Restore’ in iTunes.
Step 7. Select the downloaded IPSW file in the first step.
Step 8. Click ‘Restore’.
After a process that can take several minutes and several restarts of the device… it will return to iOS 12 if there is no problem. However, keep in mind that the process has been a restoration of the system, so the iPhone / iPad and all its data is completely deleted and formatted. There are several options, but don’t try to restore an iOS 13 backup to iOS 12 because it doesn’t work:
● Have a previous backup of iOS 12 and before installing iOS 13 to restore it now.
● Save important data externally and copy it back to the restored device.
● In step 6 instead of clicking on ‘Restore’ click on ‘Update’. However, it can cause problems in the use since there is confrontation of data between different operating systems.
Once all this is done we will have the iPhone or iPad working again in iOS 12 and without any beta version. The next thing is to wait either for the definitive version of iOS 13 or for the iOS 13 public beta, which tends to have fewer bugs.