While using the app and a Bluetooth Headset, you will notice a degradation when you are listening to music and you are in rider chat.
This is due to a bandwidth constraint of Bluetooth.
The way Operating Systems work (iOS or Android) is to give all the bandwidth possible to the data going from the phone to the speaker (what you hear) when the microphone is not in use.
However, once you start using the microphone (for rider chat), the Operating system will automatically compress the outgoing data (to the speaker) so that the Bluetooth connection can accommodate for the incoming data (from the microphone to the phone). As a result, if you are listening to music, the compression will lower the audio quality.
This is something done by the phone, not by the FUSAR app
Note for iOS users: if you do hear a significant quality degradation when you are not using the rider chat mode, make sure to update the app to the latest version.