[Bug] cannot backup on Android 8.1, since 8.3.1 to lastest 8.3.8.

[moe-rgb]

Description
A clear and concise description of what the bug is.

Not Working on Android 8.1.

Steps To Reproduce

1. give root permission
2. tap backup
3. show the following warning in screenshot:
   [ BackupAppAction$BackupFailedException:
   com.machiav3lli.backup.actions.BaseA
   ppAction$ScriptException occurred on
   data backup: com.machiav3lli.backup.act
   ions.BaseAppAction$ScriptException: tar:
   chdir '--exclude’ - tar: chdir ‘exclude’ ]
4. End, all apps cannot be backuped, the one in the screenshot is just one of them. I also have Android 11 and Android 9 devices, NB worked normally for years. Only Android 8.1 Device has this problem on backup, since 8.3.1 to the lastest 8.3.8. Restore on Android 8 never has been tried because of no backups.
5. No log found when I tap the 'log' icon in settings. It's empty inside.

Expected behavior
Work normally, so that I can migrate app data.

Screenshots
Only if there's no clear logs, add screenshots to help explain your problem.

System Information(please complete the following information):

• Device:
• Android Version: Android 8
• ROM: (AOSP, MIUI, OOS...) Lineageos
• App's Version: 8.3.8

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Additional Notes

• If you're on the latest Test version(from the TG-Channel or Matrix-Room) please report there directly, not here.

• If you're on the latest github version:

  • Please read the FAQ first.
  • Please read all the open Issues. If one does match yours, leave a comment there if there's some extra information you can provide.

• If you're not on the latest github version. Update, then make sure that the bug is still there. If it's go further with reporting.

Thanks for reporting.