In Firebase Authentication Limits it states that new account creation limit is 100 accounts/IP address/hour. I could not find any further explanation on this, i.e. what happens if the limit is exceeded, because it is very likely that there might be more than 100 new user creation after the launch of the app or a successful marketing campaign.
It states that "You can schedule a temporary increase to the account creation limit in the Firebase console."
Is that a paid service? How much does it cost? How long is temporary? How often can it be scheduled?
