Why does Google OAuth2 re-ask user for permission when i send them to auth url again

Question

With the old google openid, when i sent a user (who had previously opted-in to my app) to the auth url, it would immediately redirect them back to my app.

Now, with

Answer 1

For me it was hd (hosted domain) parameter. After removal from authorization url I was given a list of users to choose for Auth. More info on hd parameter here https://developers.google.com/identity/protocols/OpenIDConnect#hd-param