When are LDAP groups pulled?


I’ve configured LDAP login and everything is OK. Groups are also assigned correctly to users.
I’ve add Oauth2 login capability and it works too.
However, when a user log in with Oauth, its LDAP groups are not populated.

I could try the remote header auth but will LDAP groups be populated then ?

More generaly, what is the auth workflow when multiple sources are enabled ?