Yama1lama,
Thanks for that additional information.
Check out where to find that option in iOS 14 here: Adjust the volume on iPhone
The specific section below may help:
"Limit the headphone volume
You can limit the maximum headphone volume for music and videos.
- Go to Settings .
- Tap Sounds & Haptics (on supported models) or Sounds (on other iPhone models).
- Tap Reduce Loud Sounds, turn on Reduce Loud Sounds, then drag the slider to choose the maximum decibel level for headphone audio.
Note: If you have Screen Time turned on in Settings, you can prevent changes to the maximum headphone volume. Go to Settings > Screen Time > Content & Privacy Restrictions > Reduce Loud Sounds, then select Don’t Allow."
Regards!