$re = '/\[.+,(.+),.+\]/m';
$str = '2021-03-01 11:43:07.689 INFO [boot-otel-tempo-provider1,24b65cc591d3a69da10f308ab41343d7,6db7a6a82703fee9] 8 --- [nio-8090-exec-5] i.o.example.flight.FlightService : Doing some work In New span ';
preg_match_all($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