To show strikeout on order item subtotal

Show a strikeout on the order item subtotal.

add_filter('woocommerce_order_formatted_line_subtotal', function ($subtotal, $item, $order) {
    $discount = $item->get_meta('_advanced_woo_discount_item_total_discount');
    if ($discount && isset($discount['discounted_price'])) {
        $quantity = $item->get_quantity();
        $regular_price = wc_price($discount['initial_price'] * $quantity);
        $sale_price = wc_price($discount['discounted_price'] * $quantity);
        return '<del>' . $regular_price . '</del>'  . '<ins>' . $sale_price . '</ins>';
    }
    return $subtotal;
}, 10, 3);