Google pricing / tiers (Google Identity Platform)

Hello,

I have been checking the Google pricing table for Google Identity Platform, and they have two tiers, tier 1 and tier 2 (https://cloud.google.com/identity-platform/pricing#identity-platform-pri...).

Does this module only use Oauth2 which falls under tier 1 (free up to 50k), or OIDC features too, which makes it fall under tier 2, which is free only for up to 50 monthly users?

If the module falls under tier 2, is it possible to make it fall under tier 1, as the pricing difference is quite significant? For 50k users, it is 0€ vs 750€.