Datetime days between difference between php8.0 and php8.1

datetime-diff.php

<?php

/**
 * Two datetimes with microseconds
 */
$from = new DateTime('2021-12-01 11:23:38.975080');
$to = new DateTime('2021-12-15 11:23:38.975066');
$daysBetween = \intval((clone $to)->diff($from)->days));
var_dump($daysBetween);

# In PHP8.0 -> 14
# In PHP8.1 -> 13

/**
 * Two datetimes without microseconds
 */
$from = new DateTime('2021-12-01 11:23:38');
$to = new DateTime('2021-12-15 11:23:38');
$daysBetween = \intval((clone $to)->diff($from)->days));
var_dump($daysBetween);

# In PHP8.0 -> 14
# In PHP8.1 -> 14

/**
 * Two datetimes with microseconds, but the second is 1 microsecond lower than
 * the first one.
 */
$from = new DateTime('2021-12-01 11:23:38.000001');
$to = new DateTime('2021-12-15 11:23:38.000000');
$daysBetween = \intval((clone $to)->diff($from)->days));
var_dump($daysBetween);

# In PHP8.0 -> 14
# In PHP8.1 -> 13