I noticed this behavior since I got my Pixel 6A and installed Graphene as soon as I unboxed it, it was November 2022. Basically I can use the Bluetooth for calling and music just fine. However when in idle state (that is, no call and no music playing, just connected), my car shows that my phone has been disconnected after around 5 min of idle, and then 15 sec later it gets reconnected automatically. And on and on, every 5 minute or so it disconnects and then reconnects.
I tried multiple phones with that car and no one kept doing that.
Moreover at some point, around January I suppose, I was not having these issues with Pixel 6a but they re-appeared short after, or after an update or a reboot, I don't know.
Eventually, I would like to ask if I can tweak some settings in developer area of the phone where a bunch of Bluetooth settings are present. What should I tweak to try to solve this?