Code snippet to reject login for admin/authors from the regular login url

protect_login_for_admin_roles.php

<?php

/*
 * Code snippet to reject login for admin/authors from the regular login url
 * In this example, people who have edit_posts permission is require special url string to login
 * The URL need to be: https://yourdomain.com/wp-login.php?salt=your_random_url_string
 * For normal users they can login without the special salt
 * But If author or admin try to login it will reject the authentication
 * 
 */
add_action('wp_login', function ($username, $user) {

    // your target salt. Feel free to customize this
    $urlParamString = 'your_random_url_string';

    if (user_can($user, 'edit_posts')) {
        $refer = wp_get_referer();
        if (!strpos($refer, $urlParamString)) {
            wp_logout();
            wp_redirect(wp_login_url());
            exit();
        }
    }
}, 1, 2);