Comment by reaperducer

Coincidentally, today I tried to log in to Google AdSense for the first time in months using Firefox. Google simply will not permit it.

  Couldn’t sign you in
  This browser or app may not be secure. Learn more
  Try using a different browser. If you’re already   using a supported browser, you can try again to sign in.

I checked, and my version of Firefox is up to date. I know I could play reindeer games with the user agent, but I shouldn't have to.

Surprisingly, to me, it had no problem with Duck's browser. I thought that would be on the forbidden-by-Google list, too.