According to a dedicated page published by Apple for the program, the faulty AirPods Pros may be showing the following issues when used:
Crackling or static sounds that increase in loud environments, with exercise or while talking on the phone Active Noise Cancellation not working as expected, such as a loss of bass sound, or an increase in background sounds, such as street or airplane noise
In case your AirPods Pros are exhibiting these problems as well, you can get them fixed or replaced from Apple for free. The program covers AirPods Pro units up to two years after their retail date, so even if your limited warranty has expired, this problem will be fixed by Apple for free. Unfortunately, Apple doesn’t have a serial number database for the affected units, which means you can’t check if your AirPods Pros are eligible for a replacement online. If you are facing these issues, you will have to go to an Apple Authorised Service Provider, or visit an Apple Retail Store to get your AirPods checked, and see if they are covered under the program. You can find more details about the replacement program here. Do note that the program doesn’t cover AirPods or AirPods 2, and it doesn’t cover the charging case for the AirPods Pro. If your earbuds are eligible to be replaced or repaired, Apple will take the necessary steps, but you won’t be getting a fresh charging case alongside your new replacement earphones.