I just updated to the latest firmware and I still see that when NFC reader reads the tag from the smartphone it does change all the time. And it also shows only 8 bytes of the address and not all 16 as with the supplied cards.

Is there really no way to reliably identify the user by the Android  smartphone?  I think that such a  Funcionality is super  important.

Please let the NFC reader read the tag from the smartphone and then download a debug log from the Warp2 and upload it here.

This won't work. Android smartphones periodically change the NFC tag ID. The only way to change this (as far as I know) is to use some kind of NFC card emulation app that (depending on your smartphone) will only work if you root your phone. See for example here: https://stackoverflow.com/questions/19764476/host-based-card-emulation-with-fixed-card-id

We've thought about not using a tag's ID but instead the first payload page (see here: https://github.com/Tinkerforge/esp32-firmware/issues/90) but nobody had the time to implement this yet.

It works in the ENEL charging platform here in italy where the charger will log you in even without the enel app installed.  I did setup that once and then reflashed a phone and it still authorizes me.  Looking forward, I have this uni campus project where a lot of chargers has to be installed and distributing people cards would be a PITA.