Airpods dropping calls / proximity sensor active

My airpods dropping calls from time to time and I wondered why. Now I´ve recognized that the proximity sensor of the phone is not active during an call with airpods. This causes an active touchscreen, which is a problem, when you are walking with the phone in your pocket. I think this is a bug and should be solved.

Does anybody know if this issue is already on the list for the next update or how can I inform the developers about this bug?