AirPods pro cannot connect to iPhone

Before I get the reset your AirPods - recommendation, I want to point out, I did that numerous times.

It is funny, but since a week every morning when waking my iPhone 11 pro from airplane mode my AirPods pro won't connect via audio to the device. It says connected in the settings, but no sound, though the isolation feature in the pros is clearly hearable. I even can pause and start audio on the the device, yet the audio runs through the iPhone speakers not the Airpods.

Restarting bluetooth does not help, separarting the AirPods and reconnecting them does not help.

I have to restart my iPhone completely each morning to get it to work. Then for a day everything works fine and then the next day the same thing happens.

This occurred from one day to the other.

Running the lastest edition of iOS13 on the phone, updated it 2 days ago - so the problem was not solved with the update.

This is quite annoying for a 275 € device, the AirPods pro.

Any ideas or same experiences anybody?