Some users are not able authenticate to KBC using Google Sign In. We are investigating the issue.
In the meantime, please sign in using the standard email and password method.
UPDATE, Sep 22, 07:47 UTC - We have identified the issue. Google users with some special characters in name were affected. We have made changes in interaction with Google. It should resolve this issue. Fix should be deployed in two hours.
UPDATE, Sep 22, 09:55 UTC - Fix was deployed. You should be able to authenticate to KBC using Google Sign In.