AFAIK people who did not set up billing get this transition account so their access is not cut off completely.
https://groups.google.com/forum/?#!topic/firebase-talk/jWRCd...
https://groups.google.com/forum/?#!topic/firebase-talk/jWRCd...
The response from the Firebase team [2] was that no additional charges would occur based on this incident, and they've opened an incident report [3] in their dashboard.
- [1] StackOverflow Thread with users facing similar confusion https://stackoverflow.com/questions/51373671/project-upgrade...
- [2] Official Firebase response https://groups.google.com/forum/?hl=en-US#!topic/firebase-ta...
- [3] Firebase incident report for issue "Firebase Users who use Maps API get auto-upgraded to Blaze" https://status.firebase.google.com/incident/Console/18016