setTimezone exhibiting mistaken timezone

I’ve a variable for exhibiting the timezone for the occasions. The timezone for Los Angeles exhibiting right time zone (PST or PDT) routinely, however on the day when the time modifications (November seventh) the time remains to be PDT, although the time was already modified that evening and must be PST – variable $date_time_pacific.
Cannot discover the answer to point out the PST 1 day earlier.
The code under:

<li><robust>
    <?php 
        $date = get_field('start_date');
        $event_date = date("l, F j, Y", strtotime($date));

        $date_time = get_field("start_date");
        $date_time_eastern = new DateTime($date_time, new DateTimeZone('America/Los_Angeles'));

        $date_time_pacific = clone $date_time_eastern;
        $date_time_pacific->setTimezone(new DateTimeZone('America/Los_Angeles'));
      ?>
      <?php echo $event_date; ?> <?php echo $date_time_pacific->format('T'); ?>
</robust></li>