https://wccftech.com/a-small-percentage-of-iphone-12-and-iphone-12-pro-models-facing-sound-issues-due-to-failing-component/

Apple is only days short to announce its upcoming iPhone 13 lineup. However, the company has determined sound issues in some models of the iPhone 12 models. Hence, Apple has announced a new service program for the affected iPhone 12 and iPhone 12 models which will address the sound issues. Scroll down to read more details on the subject.

Apple states that a "very small percentage" of iPhone 12 and iPhone 12 Pro models are affected by sound issues and subject to free service from Apple Stores. The sound issues are being caused by a component that can fail to work on the receiver module. If you have bought your iPhone 12 or iPhone 12 Pro model between October 2020 and April 2021, it is possible that your device is affected.