I don't own AirPod Pros but I have had that issue with my 1st Gen AirPods. The funny thing is sometimes the sound fails with the left and sometimes it fails with the right. Sometimes the issue just goes away when I put them in my case and take them out, sometimes I have to do a reset, and other times I've had to do a reset more than once. I have also sometimes had my AirPods fully charged only to have the phone tell me one of my AirPods was barely charged. (I have had this issue before iOS 13.)
I will state that I also own a pair of 2nd Gen AirPods, and they're also hooked up to my iPhone so that might be the problem. (I have yet to experience this issue with my 2nd Gen AirPods.)