在php中不能正确计算日期差异

$date1 = strtotime('2022-01-01');
$date2 = strtotime('2022-02-01');

$diff = date_diff(date_create(date('Y-m-d', $date1)), date_create(date('Y-m-d', $date2)));

echo $diff->format('%R%a days');

$date1 = strtotime('2022-01-01');
$date2 = strtotime('2022-02-01');

$diff = ($date2 - $date1) / (60 * 60 * 24);

echo $diff . ' days';