$re = '/\"id\\\\\":\\\\\"(?<id>[^\\\\]+)/m';
$str = '{"line":"c5fd03529388e8d6 INFO 2021-06-10 04:11:02,966 [reactor-http-epoll-2] com.test.content.test.external.SnsPayloadEventSender Sent payload event id=9a67e81d-5ae3-5e84-b1f7-b126c9f5c787 for payload event={\\"approvalDate\\":\\"2015-06-10T04:11:02.128Z\\",\\"adenceIds\\":[],\\"adenceTargets\\":[],\\"collGroupId\\":\\"008be467-6c78-4079-94f0-70e2d6cc4003\\",\\"collections\\":[\\"d879aa85-698c-41a1-b066-a8ecdf6b8a9c\\",\\"d879aa85-698c-41a1-b066-a8ecdf6b8a9c\\"],\\"endSchedule\\":\\"3000-01-01T19:00:00.000Z\\",\\"id\\":\\"0827ce61-e07c-4b51-a052-681dcc94fa2f\\",\\"language\\":\\"ja\\",\\"mplace\\":\\"JP\\",\\"nodeVersion\\":null,\\"payloadType\\":\\"thread\\",\\"preview\\":false,\\"resourceSubType\\":\\"thread\\",\\"resourceType\\":\\"thread\\",\\"startSchedule\\":\\"2021-03-26T22:00:28.000Z\\",\\"type\\":\\"P\\",\\"version\\":\\"1622644250765\\"}","source":"stdout","tag":"21c5897e605c","attrs":{"application":"test","team":"test"}}';
preg_match_all($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