Left AirPod is quieter than the right

Let your wife, partner or friend try them to see if they get the same response. But do it with your device for testing uniformity.

How to clean your:

AirPods --> How to clean your AirPods - Apple Support

AirPods Pro —> How to clean your AirPods Pro - Apple Support

AirPods Max —> How to clean your AirPods Max - Apple Support

- Customize headphone audio levels on your iPhone or iPad --> Customize headphone audio levels on your iPhone or iPad - Apple Support

Check the audio level balance. Go to Settings > Accessibility > Audio & Visual > Balance

(On older systems: Settings > General > Accessibility)