What are the potential pitfalls of using microtime with a specific date in PHP?

When using microtime with a specific date in PHP, the potential pitfall is that the microtime function returns the current Unix timestamp in microseconds, which may not be accurate when combined with a specific date. To solve this issue, you can use the DateTime class to create a specific date object and then calculate the microtime difference from that date.

$date = new DateTime('2022-01-01 00:00:00');
$microtime = microtime(true);
$microtime_diff = ($microtime - $date->getTimestamp()) * 1000;

echo $microtime_diff;