Apple has posted a new iPhone 12 and iPhone 12 Pro Service Program for No Sound Issues. Apple's notice reads: "Apple has determined that a very small percentage of iPhone 12 and iPhone 12 Pro devices may experience sound issues due to a component that might fail on the receiver module. Affected devices were manufactured between October 2020 and April 2021.
If your iPhone 12 or iPhone 12 Pro does not emit sound from the receiver when you make or receive calls, it may be eligible for service. Apple or an Apple Authorized Service Provider will service eligible devices, free of charge. iPhone 12 mini and iPhone 12 Pro Max models are not part of this program."
For more details about the repair program, check out Apple's full announcement.