The date must be something that strtotime() is able to parse:
$finder->date('since yesterday');
$finder->date('until 2 days ago');
$finder->date('> now - 2 hours');
$finder->date('>= 2005-10-15');
See also:
strtotime
See also:
DateRangeFilterIterator
See also:
DateComparator
publicdate ( string$date ) : Finder | Symfony\Component\Finder\SplFileInfo[]