Is Gmail log-in broken under Safari 13?

I upgraded to Safari 13 today. After that, I happened to be trying to add a new Gmail account to my Mail app. The app prompted me to authentiate in Safari. But when I clicked "Open Safari", the only thing happened is... The Safari app opened. But no Google log-in page was opened. If I remember correctly, everything works fine under Safari 12. A Google log-in page will appear and let me log in.

This is the butten I clicked.