It's not a full review. I just want to raise the awareness of this issue. I suspect Airpods Pro (gen 1/2) have a very short breaking-in period. I haven't seen anyone talk about it.

I own three pairs of AirPods Pros. Two 1st gen and one 2nd gen. I bought my second pair of AirPods Pro when my first pair starts to make rattling noise. To my surprise, aside of the rattling issue, the new pair sound very different. Its tone and timbre are as neutral as it gets. Surprisingly, it turned quite a bit brighter and colder by the end of the day. It started to sound just like my old pair. I am pretty sure it's not my ears getting fatigue to high frequencies between I didn't compared them to my memories. I did side-by-side comparisons between old and new pairs when the new pairs were just opened and after some time.

Then the Airpods Pro 2 came out. The same thing happened again. Brand new pairs sounded neutral and then turned brighter. It baffles me because AirPods Pros have internal mics that adjust sound signature towards neutral.

To AirPods Pro gen 1/2 owners, have you noticed your AirPods Pro sound different from brand new pairs?