So, wow. I used my Pros extensively when they first came out since I was traveling for work quite a bit, but haven't had them on in several months. Today I confirmed I had the new firmware and put them on for a listen. Totally different sound signature than when I bought them. Anemic bass and significantly lower volume. Mine are also now failing the ear-tip test, and they never failed one time when I first had them.
Earlier in this thread someone made the claim that Apple had to dial back the ANC and bass/volume to avoid damaging the drivers. Based on what I'm hearing, that seems like a reasonable explanation.
For whatever reason I've rarely been impacted by commonly reported hardware issues, e.g. the infamous butterfly keyboard problems. Not this time. I can't believe this is not more widely reported.