Run the check
Play the same audio with the microphone unused, then start a local capture.
Record the selected input and output devices before and after.
Compare with a separate microphone or wired output without changing the audio source.
Read the result
Quality changing only when capture starts points to the active audio route.
Limits and next step
Available Bluetooth profiles and controls depend on the OS and headset.
Repeat the check after changing one setting or connection. Keep a record of what changed before deciding whether the device needs service.