This has been documented by a multitude of users.
https://www.reddit.com/r/AirpodsPro/comments/1nqf02b/new_airpod_pros_3_have_static_sound_in_left_side/
https://www.reddit.com/r/airpods/comments/1nr9bux/my_opinion_on_airpods_pro_3_from_an_airpods_pro_2/
https://www.reddit.com/r/AirpodsPro/comments/1nl2fem/ocean_static_noise_with_airpods_pro_3_anyone_else/
Apple has not responded to any of this in the public domain other than giving folks replacements; for every user on these forums a replacement has NOT resolved the issue (because it's likely a design failure or a firmware issue across the board for people with specific ear shapes and/or hearing sensitivities). I have inquired whether people with units manufactured in Vietnam vs. India vs. China can confirm whether the issue persists, and there is no clear pattern, meaning that it's likely universal (if we assume the same microphones are being sourced to each unit).
My working theory is that the anti-wave pattern being generated in the AAP3 is overly aggressive changing the noise floor envelope which is very audible to a large subset of customers -- this is how they are able to achieve their purported 2x ANC of APP2 over APP3 claim. If we assume this is not a sourcing / manufacturer defect in the microphones (which we cannot rule out), we need confirmation from Apple that the ANC anti-wave pattern is in fact generating an audible white noise / hiss / low-fan air wooshing that users are experienceing. At this point, Apple not even acknowlding this in the open (but in their Genius Bars repeatedly) is gas-lighting consumers.
The clear way to replicate the audible noise is to enable off-mode and toggle between that and noise-cancellination; as soon as you toggle on noise cancellation mode, you will hear an air-wooshing sound (to different degrees deppending on your ear shape and/or sensitivity); prior APP2s DO NOT yeild this audible noise when in noise cancelling mode because the ANC anti-wave pattern and/or microphones employed are dialed in appopriately for all.
People should continue to add comments to this thread.