there is no data to track, or rather, your phone will be the only device that has the ability to track data...
it generates and transmits random numbers (just that, random numbers, nothing else), and looks for other random numbers that were transmitted.
if you get infected, those random numbers get uploaded to some location, and then other phones can check if they've seen any of the uploaded numbers.
if a match is found, the owner of that device get's a notification to go get tested (or self quarantine, or whatever), data doesn't get exposed even in this case.
there just isn't anything there to track...
of course, this explanation is a gross simplification of the actual protocol, but still, should be accurate enough
your phone already knows more about you than will be collected by this protocol/API, so you loose nothing in terms of privacy / trackability. this protocol/API just enables contact tracing in a responsible way.