The code is displaying 'Y' as 1969 because the third argument passed to the mktime() function is $today-8 instead of $thisYear.
Here is the corrected code:
Code:
<?php
$today = date("d");
$thisMonth = date("m");
$thisYear = date("Y");
echo date("M d Y", mktime(0,0,0, $thisMonth, $today-8, $thisYear));
?>
This will display the date 8 days ago in the format "Jan 6 2023".