Hello, @Jubaer,
Actually, It’s not the theme issue it’s the domain authentication issue. It will be fixed from the Google search console. Here is an article I found for the same problem: https://discuss.redash.io/t/google-oauth-not-working-error-401-invalid-client/6101 check this and also watch this video for a better reference: https://www.youtube.com/watch?v=Jv8Oi2IrXsk
Regards 8Themes Team.