I know what happened.
They have done an update of the pricing system, see this post on their blog:
It seems that we can choose between the new way of usage, with unlimited (but rated) requests, or as before with up to 500 fast request and then it goes to slow.
But I don’t get what they would mean with “unlimited-with-rate-limits model”: will we pay an extra costs eventually?
What I do not understand is that we have not enabled Usage-based Pricing Settings, if we will still be charged or how it will be managed.
Any info about that will be clarifying
Thanks