Youtube Data API Search: list return unrealiable result?

For instance,

//php code  $client = new Google_Client();  $client->setDeveloperKey($DEVELOPER_KEY);  $youtube = new Google_Service_YouTube($client);  $searchResponse = $youtube->search->listSearch('id', array('part' => "snippet",'type' => "channel",'maxResults' => "50",'order' => "viewCount",'publishedAfter' => "2021-10-25T00:00:00Z",'publishedBefore' => "2021-10-25T23:59:59Z",'regionCode' => "JP",));

This query return only 9 channels (and the regionCode of several channels are not JP).There should be more than 9 channels under this filter because channel id such as UCUJNWCiqMT_UudVRSSGZ3SA satisfy all conditions (proved by the information return by Channels API) but was not contained in those 9 channels.I have tried to add condition 'safeSearch' => "none", but it doesn't work either.

This is just an example to show that Youtube Data API Search: list seems only return a small piece of data (at least in the case of channels) which were unrealiable.

Was my code wrong or this API does only provide incomplete results?How could I get realiable results?

Best regards