Do you have a source for the “even when your device is supposedly off” part? I know iPhones have tracking enabled when off, but there’s no way they’re using Bluetooth to find these devices and reporting back. I can’t find a source for that at all.
But even then, it’s still pretty private because there’s no way to reverse track an AirTag. I don’t even think they can do that internally at Apple.
They have a bot symbol next to their name. But anyone can turn that on in their settings.