This is my first experience at a hotel using a mobile phone app as a keycard. It seems to transmit using BLE (Bluetooth Low-Energy).
Great for convenience, but I'm not sure how trustworthy it is, even though the permissions aren't egregious. I'll be disabling or uninstalling it until the next time I stay at one of these properties just to be safe.
@voltronic I always uninstall travel apps after travel is done. Hotels, airlines, etc.