Login with EA fails in Firefox

When i click on login, Firefox opens the ea page.

I enter my username and password, click signin and nothing happens.

Firefox DevTools say there is a post request to signin.ea.com but no login takes place.

Kyber Launcher stays at “failed to find auth code” with a backtrace of a few lines of “unknown” and 19 basethreadinithunk and 20 “rtluserthreadstart”

I vaguely remember that FF and login redirect is a bit problematic, but i have no clue how to get this solved,