Set random dates for events ACF/WP

func.php

<?php
  $allevents = wp_get_recent_posts(array(
      'showposts' => '-1',
      'post_type' => 'events'
  ));
  $start = strtotime("10 October 2018");

  //End point of our date range.
  $end = strtotime("22 November 2020");

    foreach ($allevents as $ev) {
	    $timestamp = mt_rand($start, $end);
	    $randomDate = date("Y/m/d", $timestamp);
        update_field('field_5bd04e09e2fdc', $randomDate, $ev['ID']);
	    var_dump($randomDate, get_field('start_date', $ev['ID']));
	    echo '<br>';
    }
    ?>