Hi, here is the phonak answer:
"Good afternoon,
Thank you for contacting Phonak with your inquiry. We have been made aware that the Audeo Marvel is not staying paired to the new iPhone 11. Our Product Management team will be reaching out to Apple to determine what has changed to cause this incompatibility. Unfortunately, we do not have an answer to give at the moment. We will hold on to your email and let you know once we hear of an update. Thank you for your patience.
Best Regards,
Consumer Technical Support"
We just have to wait like last year
PS. I solved temporarily using the bluetooth of the Apple Watch Series 4 connected with the Marvels. Now I can make calls and listen to music thanks to the apple watch.