Maps and Firebase - Billing accounts

Here's a funny thing that I just found out in regards to Firebase (Notifier) and Google Maps. Let me know if I'm doing something wrong...

Firebase Spark plan (free) requires no billing account to work.

Google Maps API (free) does require a billing account to work.

What happens to my Firebase project if I add or remove billing accounts for that project in the Google Cloud Console?

If a billing account is added to a project in the Google Cloud Console, the same project will automatically be upgraded to the Firebase Blaze plan if that project is currently on the Spark or Flame plan.
In contrast, if an existing active billing account is removed from a project in the Google Cloud Console, that project will be downgraded to the Firebase Spark plan.

https://firebase.google.com/support/faq/

Any ideas on how to get around this? Right now I had to remove our billing account, so while notifier works, our Maps are coming up blank. I don't want to have to make two separate accounts.