Preventing Admin Login with Subscriber-Only Access

Hi everyone,

I need some help. When users log in, I want them to get an error message if they enter a username and password that isn’t for a subscriber. This is to prevent anyone from guessing admin credentials. I tried using a custom plugin with the code below, but it still allows admin logins. Any advice?

function custom_check_user_role_before_auth($user, $username, $password) {

    if (is_wp_error($user)) {
        return $user;
    }

    $user_obj = get_user_by('login', $username);

    if ($user_obj && is_array($user_obj->roles) && !in_array('subscriber', $user_obj->roles)) {
        return new WP_Error(
            'invalid_username',
            sprintf(
                __('Error: The username %s is not registered on this site. If you are unsure of your username, try your email address instead.', 'domain.com'),
                $username
            )
        );
    }

    return $user;
}
add_filter('authenticate', 'custom_check_user_role_before_auth', 5, 3);

Could my code be conflicting with Paid Member Subscriptions?

Thanks!