TL;DR Has anyone else had issues with being heard when using a Bluetooth headset on Android 12? Any fixes?

Longer version - I have been using a bluetooth in-helmet headset for talking to motorbike riding buddies for a few years. It connects to my Android handset and we talk (using an app) to maintain always on comms. This has worked over at least three Samsung handsets (S8, S9 and Note 20). However, since upgrading my Note20 to Android 12 the mic volume has suffered and everyone else struggles to hear me. Pretty sure its the Android upgrade as I can 'fix' the problem by going back to an older handset that has not been upgraded to Android 12. Nothing else has changed. It is the same across multiple apps (Whatsapp, FB Messenger, jitsi conferencing app however it does NOT impact phone call volume in the same scenario). I've done a few searches but have not turned up anything useful. Anyone else had this or better knows how to fix it?