Apple has indeed nerfed ANC on the AirPods Max through automatic software update
xda-developers.com
xda-developers.com
https://www.rtings.com/headphones/reviews/apple/airpods-max-...
"…after updating the headphones to firmware 4E71, their active noise cancelling (ANC) system blocks out a bit less noise between the mid-bass to high-bass range than the previous firmware. […] …it's a relatively minor difference. The ANC can still reduce sounds like ambient chatter and the high-pitched whirl of AC units extremely well."
Why would Apple do this? RTINGS also has a likely explanation:
"Users have reported high cabin pressure when using their unit's ANC. It's a pressure-like feeling inside your ears when the ANC is on and is a similar sensation to when a plane ascends and descends. It's caused by your brain perceiving the lack of low-frequency sound as a pressure difference between the inner and outer ear, which can become uncomfortable."
> When it comes to the mid and treble ranges, this firmware update has slightly changed the level of isolation, but it's a relatively minor difference.
Furthermore a comment indicates that the noise generator they might have used has slightly changed as well. I'm not sure what the outcry is all about. Most people experiencing changes in ANC usually have cruft on their microphones and that issue is easily fixed with a q-tip.
> We've tested 'Noise Isolation' with a couple of other firmware updates. We didn't get noticeable differences with firmware update 2B588, released in November 2019. Apple may have tweaked the ANC in this update, but not enough to noticeably impact the overall performance. There have also been user reports that the ANC became worse after firmware update 2C54, released in December 2019. After updating this firmware, our results showed a fairly significant drop in isolation performance, primarily in the bass range. This means that with ANC turned on, they won't do nearly as good a job blocking out the low engine rumbles of planes or buses as they did before this update. Our latest retest uses firmware update 4A400, released in October 2021, which shows that their overall noise isolation performance has been further weakened. [0]
[0] https://www.rtings.com/headphones/reviews/apple/airpods-pro-...
In the case of an item, weapon, ability (etc..) which is too powerful (and thus detrimental to game balance), the developers make it less effective by changing it's in game statistics - frequently lowering the potency of the strongest characteristics, or by changing how it behaves completely.
Such changes, when overdone by the developers, are said to "nerf" the item - to make it a harmless, "nerf" equivalent of it's former self (Nerf itself being a popular brand of foam activity toys).
"This spell is getting hit with the nerf bat in the next patch" -- is an example of it in use.