$d1p = '(\d{4})[-/.](\d{2})[-/.](\d{2})';
	$d2p = '(\d{2})[-/.](\d{2})[-/.](\d{4})';
	$t1p = '(\d{2})[-:](\d{2})';
	$t2p = '(\d{2})[-:](\d{2})[-:](\d{2})';
	$sp = '[  T@]';
	if (preg_match("~^{$d1p}{$sp}{$t1p}$~", $value, $m)) {

$d1p = '(\d{4})[-/.](\d{2})[-/.](\d{2})';
$t1p = '(\d{2})[-:](\d{2})';
$sp = '[  T@]';
$str = '2021-05-27 10:11';
$re = "~^{$d1p}{$sp}{$t1p}$~";
$ret = preg_match($re, $str, $m);
print_r([$re, $str, $ret, $m]);