Expected output vs. Actual output

campaign.php

<?php

$format = 'Va*';
die(print_r(unpack($format, pack($format, time(), "test")), true ));

/**
 * Expected output:
 * Array
 * (
 *    [V] => 1635617836
 *    [a*] => test
 * )
 * 
 * Actual output:
 * Array
 * (
 *    [V*] => 1635617836
 * )
 */