Conditional shipping rate cache invalidation

shipping-rate-cache-invalidation.php

<?php
/**
 * This implementation will disable the shipping rate cache.
 * To conditionally disable the cache, replace `wp_rand()` with a conditional value. 
 * Changing the conditional value will invalidate the cache.
 * Example: A hidden form field or a query string parameter.
 */
function wc_shipping_rate_cache_invalidation( $packages ) {
	foreach ( $packages as &$package ) {
		$package['rate_cache'] = wp_rand();
	}

	return $packages;
}
add_filter( 'woocommerce_cart_shipping_packages', 'wc_shipping_rate_cache_invalidation', 100 );