Alarm volume on iPhone when connected to Headphone

I use my iPhone's alarm to wake up.

I also use my iPhone with wired headphones (using the usb-c to jack adapter) in the evenings to listen to music and podcasts, and often fall asleep while doing so.

When the alarm rings in the morning, while the headphones are plugged, it is VERY loud. This results in a lot of stress, elevated heart rate, and a very bad waking up experience.

I am guessing this may be done on purpose, maybe "if you use headphones, the iPhone's speaker needs to be louder so you can hear it". But this makes little sense - instead, the alarm should just play both on the phone's speaker at a normal volume and in the headphones.

Or maybe this is a bug.

In any case,

• is this expected?
• is there any way to disable this behavior?

Thank you.

[Re-Titled By Moderator]