Here is how I would work around this issue with the star field as an example. This will work for both cloned and non-cloned versions of the same field.
$field_key = 'field_5d49b2ff396b6';
foreach ($_POST['acf'] as $key => $value) {
if (substr($key, -strlen($field_key)) === $field_key) {
$start = new DateTime($value);
break;
}
}
If I was going to do this a lot then I’d probably build a function that searches the input to find the right value.
