Recalculate the order totals (including taxes) for trial subscriptions: https://woocommerce.com/document/subscriptions/develop/action-reference/#payment-and-renewal-actions

recalculate-order-totals-including-taxes.php

add_action('woocommerce_scheduled_subscription_payment', 'recalculate_taxes_before_payment', 10, 1);

function recalculate_taxes_before_payment($subscription_id) {
    $subscription = wcs_get_subscription($subscription_id);

    if ($subscription) {
        foreach ($subscription->get_related_orders() as $renewal_order_id) {
            $renewal_order = wc_get_order($renewal_order_id);

            if ($renewal_order && 'pending' === $renewal_order->get_status()) {
                // Recalculate totals, including taxes
                $renewal_order->calculate_totals();
                $renewal_order->save(); // Save the updated totals to the order
            }
        }
    }
}