“You save €10” on sale products

<?php

add_action(
	'woocommerce_single_product_summary',
	static function () {
		global $product;
		if ( ! $product instanceof WC_Product || ! $product->is_on_sale() || $product->is_type( 'variable' ) ) {
			return;
		}
		$regular = (float) $product->get_regular_price();
		$sale    = (float) $product->get_sale_price();
		if ( $regular > $sale ) {
			printf(
				'<p class="snipfire-you-save">You save %1$s (%2$d%%)</p>',
				wp_kses_post( wc_price( wc_get_price_to_display( $product, array( 'price' => $regular - $sale ) ) ) ),
				(int) round( ( $regular - $sale ) / $regular * 100 )
			);
		}
	},
	11
);