日期差异明天日期

Question

我有约会

object(DateTime)[44]
  public 'date' => string '1980-11-21 00:00:00.000000' (length=26)
  public 'timezone_type' => int 3
  public 'timezone' => string 'Europe/Moscow' (length=13)

/srv/www/vhosts/drevlanka.ru/work/support/functions.inc.php:3109:
object(DateTime)[48]
  public 'date' => string '2019-11-20 00:00:00.000000' (length=26)
  public 'timezone_type' => int 3
  public 'timezone' => string 'Europe/Moscow' (length=13)

和代码

    $interval = $dateTwo->diff($birthdate);
      //  $interval = $birthdate->diff($dateTwo);
        var_dump($interval);

如果$bistdate<$dateTwo，我有当前间隔，但是如果$bistdate>$dateTwo，此函数返回不正确的天差。