Bluetooth headset vanishes after selecting

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Steps to reproduce

1. Start a call
2. select sound source as bluetooth
3. get a calling sound in the headphone
4. sound jumps back to the phone and bluetooth gone as a choice untill you restart a new call

Expected behaviour

I should keep the call in the headset

Actual behaviour

It jumps back to the phone

Device brand and model

Google pixel 7 pro

Android version

14

Nextcloud Talk app version

19.0.8

Nextcloud server version

No response

Talk version

20.0.0 RC1

Custom Signaling server configured

Yes (specify version in Additional Information)

Custom TURN server configured

Yes

Custom STUN server configured

Yes

Android logs

na

Server log

Not applicable

Additional information

Tried with several headsets. Reset phone and bluetooth.

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It works on the same phone with loads of other different meeting/call apps.