Perhaps, they added, Apple could add a warning message when using the Control Panel toggles that alerts the user that tapping on its Bluetooth icon doesn’t completely shut off Bluetooth and their iPhone can still interact with proximity-activated beacons, such as Bochs’ contraption. So they are saying “off” isn’t really off if you do it in the control center, you have so go into settings to completely turn it off.
I don’t know if it turns itself black on (blue) when something is trying to connect.