woocommerce_order_discount_to_display

// Modifier la valeur avec le filtre 'woocommerce_order_discount_to_display'
add_filter('woocommerce_order_discount_to_display', 'ma_fonction_filtre', 10, 1);

function ma_fonction_filtre(wc_price( $this->get_total_discount( 'excl' === $tax_display) {
    // Modifier la valeur
    return wc_price( $this->get_total_discount( 'excl' === $tax_display;
}