Mine are on 2B588 and I think I bought them late enough that I never even had the original firmware to compare. I do know that when I first put them in I thought the power went out in my house (due the sudden lack of noise). I would like to know if I'm crazy or if these don't stay in ears well at all. Kind of the opposite of what you would expect from an earpod like this but I can get them to fall out in <10 seconds when eating with them in. Even when I'm not moving my jaw they have a habit of slowly sliding out.
And before I get asked about tip size, I've tried all of them and done fit tests on all of them. Fit tests always pass, and the pods always fall out. I even tried different sizes on different ears over time to compare the two but they seem to fall out at the same rate. I just (like as in 2 hours ago) broke down and bought some foam tips from Amazon to see if that helps.
It's really disappointing because my original AirPods were so magical and now I kind of don't like wearing the Pro's. I've considered more than once just buying AirPod 2's and giving up.