The Firebase Authentication is processing data exclusively in the United States, and is therefore not GDPR compliant. However, they are saying on the same site that:
Firebase has moved to reliance on Standard Contractual Clauses for relevant data transfers, which, as per the ruling, can continue to be a valid legal mechanism to transfer data under the GDPR
They are also saying that:
The European Commission approved new versions of the Standard Contractual Clauses on June 4, 2021
Google Cloud Platform have some Eu Standard Contractual Clauses on their website, and they have announced that they have incorporated various modules of the new EU SCCs. Can we therefore still use Firebase Authentication and be GDPR compliant?
In Updated data processing terms to reflect new EU Standard Contractual Clauses doc, it is mentioned about the new whitepaper
Yes, it will comes under GDPR compliant as mentioned in the [Page No. 12] of new whitepaper which explains about Customers in Adequate or Non-Adequate Countries with Google Service Providers in Non-Adequate Countries as :
For more information, you can also refer to the blog and video which explains that the data collected by Firebase Analytics would fall under the jurisdiction of the GDPR if used to track residents of the EU