Before testing, please disable developer options, enable "Notify about system process crashes" in Settings > Security and reboot. This will avoid issues caused by developer settings and will provide you with crash logs for crashes of Bluetooth related services which you can provide here.
Please provide a list of the Bluetooth devices you use including the device type and ideally the specific brand/model of device, whether it is working well for you before Android 14 QPR2 and whether it's working well since updating to Android 14 QPR2. If there are any crash logs , please include them.
The latest 3 releases of GrapheneOS (2024030800, 2024030700 and 2024030600) are based on Android 14 QPR2 and 2024030800 is the first to reach the Stable channel. No issues were reported with Bluetooth with any of our 3 initial releases based on Android 14 QPR2 while they were in Alpha or Beta so it must be working fine for most users and with most devices. It would be helpful if people could provide the requested feedback so we can determine which devices have issues.