Woocommerce - Remove products from Filter where the variation is out of stock - Replace size with your variation attribute slug

functions.php

/**
 * Remove produtos que a variação não tem em estoque
 * Removes products from Filter where the variation is out of stock 
 * @see https://github.com/woocommerce/woocommerce/issues/20689
 */
add_action( 'woocommerce_before_shop_loop_item_title', 'remove_out_of_stock_products_from_active_filter' );
function remove_out_of_stock_products_from_active_filter(){
    if (isset($_GET['filter_size'])) {
        global $product;
        if ($product->is_type('variable')) {
            $variations   = $product->get_available_variations();
			$is_available = false;

            foreach ($variations as $variation) {
                if (isset($variation['attributes']['attribute_pa_size'])) {
                    if ($variation['attributes']['attribute_pa_size'] == $_GET['filter_size'] && $variation['is_in_stock']){
                        $is_available = true;
                    }
                }
            }

            if (!$is_available) {
                global $product;
                $id = $product->get_id();
                echo "
                    <style>
                        .woocommerce-result-count { visibility: hidden }
                        .post-$id { display: none !important }
                        .woocommerce-pagination { display: none !important }
                    </style>
                ";
            }
        }   
    }
}