headphone volume too high

OK.....I don't do that. See if this helps --> Headphone notifications on your iPhone, iPod touch, or Apple Watch - Apple Support

Note: If you live in a country or jurisdiction, which mandates these notifications by law, you may not have the ability to turn them off. Apple is simply doing what may be required by law and if that is your situation, you can thank the ministries of health where you live for this behavior.

Read this link and pay particular attention the section entitled Classify your Bluetooth Device --> Set up and listen to Bluetooth devices on iPhone - Apple Support