Hi User2327,
welcome to the Apple (user-to-user) Community.
Re: "Left AirPod low sound"
You might want to check the volume level on the AirPods themselves:
Pause, skip, and adjust volume with your AirPods and AirPods Pro - Apple Support
You can check or change your settings: (Eg: You can set Microphone to left, right, or automatic)
How to: Change the settings of your AirPods and AirPods Pro - Apple Support
Also: What to do: If your left or right AirPod isn't working - Apple Support
Eg: Says (amongst other tips) “Go to Settings > Accessibility > Audio/Visual > Balance,
and make sure that the balance is set in the middle”
You may also want to: Customize headphone audio levels on your iPhone or iPad - Apple Support
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If needed:
AirPods Support Website:
Find all the topics, resources, and contact options you need for your AirPods....
AirPods Support - Official Apple Support
All the best :-)