This snippet belong to fluxair site

fluxair.php

add_action( 'wfacp_before_process_checkout_template_loader', function () {
    add_filter( 'woocommerce_no_shipping_available_html', function ( $message ) {
        
        if ( 39648 !== WFACP_Common::get_id() ) {
            return $message;
        }
        $packages = WC()->shipping()->get_packages();
        $postcode = $_REQUEST['s_postcode'];
        if ( count( $packages['rates'] ) == 0 && '' == $postcode ) {
            return WFACP_Common::default_shipping_placeholder_text();
        } else if ( count( $packages['rates'] ) == 0 && '' !== $postcode ) {
            return $message;
        }

        return $message;
    } );
} );