Hello, @Jubaer,
Yes, I know dear. On your site, you are facing an issue with the Facebook login. But as I said that the issue is not in our theme. You can also check and confirm it by checking the issue on Google. As you can check here: https://stackoverflow.com/questions/66311123/passport-js-error-401-invalid-client-the-oauth-client-was-not-found in this article you will learn about what cause of the issue and how you can fix it. The issue is in your domain authentication/verification nothing else.
Regards 8Themes Team.