Updating user meta shortcode

<?php
    function wpses_385303_change_validate() {
        if (is_user_logged_in()) {
            $user_id = get_current_user_id();
            $metas = array(
            '_nickname_validated',
            '_first_name_validated',
            '_last_name_validated',
            );


            //If the form was posted (ie. the button was clicked) in a previous request
            if (isset($_POST['validate_user'])) {
                if ($_POST['validate_user'] == $user_id) {//A little bit of security
                    foreach($metas as $my_meta) {
                        update_user_meta( $user_id, $my_meta, 'validated' )
                    }

                    return "<div class='user_updated'>Updated!</div>";
                }
            }
        }


        //Show the form
        return "<form method='post'>
            <input type='hidden' name='validate_user' value='$user_id' />
            <input type='submit' value='Validate' />
            </form>";

    }
    add_shortcode('change_validate','wpses_385303_change_validate');