In the bluetooth settings it literally states: "To improve device experience, apps and services can still scan for nearby devices at any time, even when Bluetooth is off." This can be completely turned off in scanning settings. The article title is kind of clickbaity.
Another point to make is that iOS also made it a bit harder for the user to completely turn off bluetooth and wifi from the control center since iOS 11, possibly allowing scanners and beacons to pick up these devices from passers by. Unless you directly get into the setting screen and switch it off. Sure Apple keeps Bluetooth/Wifi on for 'Find My' services but I'm pretty sure it will also be used for the contact trac…
By the way this is not for ‘Find My’ services because these only work if the device has internet connectivity. The newly announced mesh functionality is not active yet.