There is only functions to handle before user creation.
Is the migration to V2 incomplete? Where is the onUserCreated?
As you will read in the documentation on "Extend Firebase Authentication with Cloud Functions":
Cloud Functions for Firebase (2nd gen) does not provide support for the events and triggers described in this guide
In other words, Cloud Functions triggered in response to the creation and deletion of Firebase user accounts are only available in V1 for the moment (i.e. at the date of writing) .