I tried to reproduce this by creating a Vivaldi email, then creating a new Google account with it and signed up to Defold in the Vivaldi browser. It all worked fine for me. I tried logging in and out a couple of times without any problems.
@claviger we cleared your current sessions from our end, so if you try logging in again it may work better.
If you still have problems, could you try creating a fresh new google account and sign up with it to see if that works?