AirPods 2 change volume from left to right.

Hello there Tom-van,

Thank for reaching out to the Apple Support Communities! Does the volume issue happen at all on the iPhone? Does this happen when you are listening in the Music app, or in another app like Youtube, or when you are browsing the web in Safari?

First, try these steps to Reset your AirPods.

Next, check the general sound settings on your Mac:

• Apple Menu > System Preferences > Sound
• Click on the Output tab and make sure AirPods are selected as the device for sound output.
• Is the balance slider in the middle between left and right?
• Try tweaking it by sliding it just a little towards the left speaker to see if you notice a difference.
• Now, remove your AirPods and test with a different pair of Bluetooth headphones to compare.

macOS User Guide - Change the sound output settings on Mac

Let us know the results and take care!