If the "Do Not Disturb" mode on the LG device is turned on according to a schedule, the alarm clock can automatically deactivate it even if the end of the mode is after the alarm time.

Android 9 | LG UX 9.0
Turn off after Alarm -  Open the  Settings
Turn off after Alarm -  Tap on  Sound
Turn off after Alarm -  Tap on  Do not disturb
Turn off after Alarm -  Tap on desired  Schedule
Turn off after Alarm -  Enable or Disable  End if alarm rings
  1. Open the Settings
  2. Tap on Sound
  3. Tap on Do not disturb
  4. Tap on desired Schedule
  5. Enable or Disable End if alarm rings

LG Instructions
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