Hi Andy,
Please try some suggestions bellow to see if they help:
- Switch Bluetooth codec following this article: How to change bluetooth codec Windows 11 - TechBloat. You might need to disconnect and reconnect your headphones for the change to take full effect.
Disclaimer: This is a non-Microsoft website. The page appears to be providing accurate and safe information. Watch out for ads on the site that may advertise products frequently classified as PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
- Disable Hands-Free profile: Open Settings > Bluetooth & devices > Devices > More devices and printer settings > right click on your Bluetooth device -> Properties > navigate to the Services tab > Deselect Hands-free Telephony > Apply.
If you have further information, please feel free to let me know.