The latest iOS update 11.2.6 is making some users’ AirPods stream in mono, instead of stereo, meaning the same audio channel is coming out of both AirPods. The update may also be affecting the AirPods’ tap controls. Regardless, the fix is easy.
How to fix AirPod’s mono problem in iOS 11.2.6
Unpair your AirPods in the Bluetooth settings.
To unpair your AirPods, go to Settings>Bluetooth, and select in the little ⓘ icon next to your AirPods in the list. Then, select Forget This Device, and select again to confirm.