iPhone 12 mini and iPhone 12 Pro Max units not eligible
https://www.bleepingcomputer.com/news/apple/apple-launches-service-program-for-iphone-12-no-sound-issues/
Apple has announced a new free-of-charge service program for iPhone 12 and iPhone 12 Pro devices experiencing sound issues caused by a receiver module component.
According to the company, the sound problems impact a low percentage of iPhone 12 models that were made over six months between October 2020 and April 2021.