Unwanted connection to bluetooth speaker during calls

Frequently when talking on the phone - if I have a paired bluetooth device the call will suddenly connect to that device.

I've traced the issue down to the location of the bluetooth 'on screen button' during a call. If I let the phone move away from my face even a little bit, the button appears and my face activates it.

This problem is frequent and super annoying- and the only ways I've found to solve it are to turn off the bluetooth device (often in another room) or turn off bluetooth during the call.

I'd like to see either 1) the sensor that turns the screen on require the phone be further away from the caller's face ... or 2) the function or location of the button changed so this can't happen by accident.

I've had the issue on several models of iPhones over several years. Currently using and iPhone 11.