[danaris]

Because the user's device, providing the user's data to the user's Meta headphones, via a Meta app, can then record all the time and exfiltrate all that recorded data to Meta.

Or whatever other shady company wants to make headphones that sell for dirt-cheap in order to get their private spy devices into people's homes and offices.

I'm personally a bit on the fence about whether I think this is a sufficient concern to justify what Apple's doing, but AIUI this is the gist of their objection.

[AlotOfReading]

If it violates Apple's views on acceptable privacy practices, why are they approving the app? They already have guidelines against identifying information or collecting more data than absolutely required. The developer data use page is quite frank about the expectations:

    Apps on the app store are held to a high standard for privacy, security, and content because nothing is more important than maintaining users' trust. 

This is a rhetorical question, obviously. Apple is happy to stand on principle when it benefits them, and more than willing to soften or bend those principles when it'd be too difficult.

[danaris]

If a particular app only demonstrates this undesirable behavior when the phone is paired with a particular subset of headphones (or other hardware), then Apple may never notice it in App Review.