I'm not convinced this is anything that needs to be addressed, but I'm curious about what might be happening.
I have Settings -> Security & Privacy -> Exploit protection -> Turn off Bluetooth automatically set to 30 seconds. This works as expected with things like Bluetooth speakers and headphones. However Bluetooth remains on indefinitely after I disconnect my Polar H10 heart rate sensor, even after the sensor is powered down.
There are no active Bluetooth connections listed in Connected Devices. That being said, even when the sensor IS connected, nothing is actually listed as connected on the phone.
I'm guessing that there's just something strange in the way this sensor connects to the phone that causes the service to remain active after the sensor is powered off. Can anyone shed some light?