$re = '/^\d{4}\.\d{2}\.\d{2} \S.*(?:\r?\n\d{4}\.\d{2}\.\d{2}\b.*)+(?:\r?\n(?!\d{4}\.\d{2}\.\d{2}\b).*)*/mi';
$str = '2020.11.01 SOME TEXT -17,30 83 016,86
2020.10.30
2020.10.30
2020.10.30
2020.10.30
Some text that should be
matched 20.01.2020 as
multiline text
until now
2020.11.01 SOME TEXT -27,30 81 016,86
2020.10.30
Some text that should be
matched 20.01.2020 as
multiline text
until now
2020.10.30';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php