Weird tech issue
My wife bought me one of those car adapters that allow you to use Android Auto (or Apple CarPlay) wirelessly in a car that isn't equipped to do so. It works much the same as the wireless versions - you connect to the little USB fob over a local WiFi network, and Internet access is powered by your phone's cellular data. I think Bluetooth still runs through the car's system (I still get a notification that my phone has connected).
One quirk though, it looks like the fob remains powered on even if the car is turned off. I'm not sure if it stays on indefinitely or if it's the car's electrical systems keeping it powered on until they turn off. What this means is that my phone remains connected to the device, and somehow so does my Bluetooth connection.
I realized this last night as I missed a call from my wife. I only knew this because my watch alerted me to the missed call. It was my wife's theory that my phone was still connected to the car, and I confirmed that this morning after getting to work.
Now my concern is that the fob is powered on as I type, drawing power from the battery. I will have to take a look at lunch to see if that's the case - if so I'll need to unplug it when done driving for an extended period.
Update: my concerns over battery drain are alleviated, I checked and it wasn't turned on. At this point my options are to either unplug the fob when I get home or manually disconnect from it.
My 3rd option is to explore automating it, with Routines or Tasker, but I haven't figured out how to approach the problem yet.