Query Nickname rather than Display Name in custom Woocommerce plugin

I had a similar problem and solved it similar to this:

add_filter('pre_user_display_name','default_display_name');
function default_display_name($display_name) {
    if ( isset( $_POST['billing_first_name'] ) ) {
        $display_name = sanitize_text_field( $_POST['billing_first_name'] );
    }
    return $name;
}

I think, the new woocommerce changes the disyplay_name on every checkout to First_Name Last_Name. With the ‘pre_user_display_name’ you can change your own way.