If I make a call using the VOIP app, Signal call, or a Telegram call it uses my Bluetooth headset mic but if I record a voice note instead in Telegram, or Signal, or use the voice recorder it does not use it. And I can't seem to find a way to fix this. I assume it differentiates when making a 'call' and automatically uses the correct mic.
This would´t be a problem if the phone had a microphone itself but on this modified device and the microphone was removed.