Google Identity Platform password hashing algorithm

Question

Is anyone able to confirm what is the hashing algorithm used by the Google Identity Platform to store passwords? There is a considerable argument that a secure KDF like Argon2 be used, however seemingly the documentation does not state how passwords are stored (apologies if I have not found the right place in the docs). The GCP documentation on migrating users from an existing app includes many pre-existing options, some of them rather insecure (e.g. MD5, SHA) which is notably not a Google Identity Problem but rather one of the application where the users are migrating from, yet there seems to be no information what happens after the migration. Thanks a lot in advance!