I can't seem to make the oAuth flow work, with a cryptic message saying 'popup closed by user". The Google documentation tells me Google Sign-in is deprecated and new client IDs won't work. https://developers.google.com/identity/sign-in/web/sign-in So, if I'm correct, this notebook won't work for new projects and soon won't work at all.

I use this every day, so it's still working for me, but this method of Google Sign-in will be deprecated. Is your browser preventing pop-ups?