After having the AirPod Pros in my ears today I noticed they eventually would fall out. This was not an issue with the original AirPods - I could run, skip, jump, shake, use the urinal and basically do anything and they would stay in.
This video shows how the AirPod Pros do in a short little shake test.
I will go over this test and more about the AirPod Pros on Ep 488 of Today in iOS - todayinios.com