The app Blue Monitor does not collect data referring to humans.
Blue Monitor only scans Bluetooth devices, and hence collects their name
and their Mac-address. The data of BLE Bluetooth devices are cached
internally in the app. In the settings screen a user is able to clear
these data: click button CLEAR ALL. Sometimes the name and the Mac-address
are again shown immediately, because the corresponding BLE Bluetooth
devices advertises itself constantly.
There are also Bluetooth devices that are cached by Android's middleware Bluetooth stack. Blue Monitor is not able to clear the data of those cached Bluetooth devices.
Scanning BLE Bluetooth devices requires location permission. This is a requirement for the Android's middleware Bluetooth stack; it is not a requirement for the Blue Monitor app itself. This app does not retrieve any location data !