Dual Pricing for GCP Cloud Functions with Firebase

Question

I created a new GCP Project, and created a hello-world serverless cloud function from GCP Console.

I immediately get a mail that a Firebase project has been created as well, and my Cloud Function has been upgraded to 'Blaze' plan of firebase.

My question is, which pricing model should I refer?

https://cloud.google.com/functions/pricing - GCP

OR

https://firebase.google.com/pricing - Firebase