The new tips (that’s my guess, at least) also transmit vibrations into your ears much more than the old tips or third party memory foam tips. This results in a popping noise when walking or moving around, and a horrible thumping sound when running with them in. I think the latter is partially caused by the “reduce loud noises” feature incorrectly identifying vibrations from heel strikes as loud noise.
I’m glad I’m apparently not the only one experiencing these issues. I hope they’re software fixable. I filed a bug report, but radio silence on that, of course. I would sing the praises of the second gen AirPods Pro to anyone who would listen, but the 3rd gen have been a huge disappointment. I had to buy a different set of headphones for running, whereas the second gen were my daily drivers. And I’ve been through three pair of the third gen, so it’s not a one-off issue.