In the privacy settings for Vivaldi, there is a "Google Services Token" checkbox. I unchecked it. After that, it was possible to log in to Gmail, with the site claiming that my "browser is insecure". So I was forced to check it. Then it was able to log in.
What kind of special Google nonsense is this? What exactly is it, on a technical and specific level? Why does Google have some entirely custom mechanism baked into the browser? (Yes, I know that Vivaldi is just a Chromium variant.)
Does this enable them to track me in some beyond-cookies way? If not, why are they not using cookies?