I checked a few devices here and I am unable to duplicate the issue that you are reporting.
If you take your phone to the Apple Store, the first thing that the technician will do is perform a Forced Restart on the iPhone, so if you have not already tried this a few times, that might save you a trip to the service shop.
Force restart iPhone - Apple Support
Quickly press and release the UP button
Quickly press and release the DOWN button
Hold in the Side button and keep holding it for 15-20 seconds until you see the Apple logo appear in the center of the screen. Ignore the "slider" to turn the phone off and keep holding until the Apple logo appears, then release the Side button.