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This issue is very bad, and I've had it on all 3 of the sets of AirPods pros I have owned. Another issue I have had on all three is that the noise cancelling degrades over time. When you get a new set, it's kind of night and day how good they are at first. After about 6 months I would say that they noticably suck compared to how they are when you first get them, and they just continue to degrade over time. My guess i…
This might be because each were sold with the old firmware (better noise cancellation), and eventually got updated to the new firmware (better battery).
I believe what is happening is that earwax is building up in the grille on the top inside of the airpod which houses a microphone. As the sound from this microphone gets more distorted, the noise cancellation gradually stops working. You can also see this because after you've had the airpods a couple of months you will never get the ear tip fit test to pass.
Every time this has gotten to the crackling stage, Apple has replaced these without charge, even though I didn't have Applecare. They have some sort of machine in the back of the store that they use to test them, and if your set fails the test, they give you a new pair (sometimes just one).