update and delete members from the group list in Google Apps not working anymore

Question

This PHP code below has worked for years but since some days ago it has stopped working and I get an error which I show below
The purpose of this code is to update and delete members from the group list in Google Apps.

I searched a lot on Google but couldn't find an answer

Google API client used
https://github.com/googleapis/google-api-php-client

Google Workspace Admin SDK
https://developers.google.com/admin-sdk/directory/reference/rest/v1/groups

PHP CODE

if (isset($_GET['mode']))
    $mode = $_GET["mode"];
else
    $mode="TASK";

// credentials (with domain delegation)
putenv('GOOGLE_APPLICATION_CREDENTIALS=gaiviweb2web-193e903a022f.json');

// create client
$client = new Google_Client();

// apply credentials
$client->useApplicationDefaultCredentials();

// add scope api
$client->addScope(Google_Service_Directory::ADMIN_DIRECTORY_GROUP);

// impersonate user
$client->setSubject('myemail@mydomain.com');

$client->setUseBatch(true);

$batch = new Google_Http_Batch($client);

// returns a Guzzle HTTP Client
$httpClient = $client->authorize();

// service class
$service = new Google_Service_Directory($client);

$serverName = "myserver"; 
$connectionInfo = array( "Database"=>"mydb", "UID"=>"myuser", "PWD"=>"mypw");
$conn = sqlsrv_connect( $serverName, $connectionInfo);

if( $conn ) {

    $sql = "my_stored_procedure;";

    $stmt = sqlsrv_query( $conn, $sql);
    if( $stmt === false ) {
         die( print_r( sqlsrv_errors(), true));
    }
    
    // get results
    while($obj = sqlsrv_fetch_object( $stmt)) {
    
        $lista = $obj->IDGruppo;
        $action= $obj->Action;
        $email= $obj->Email;
        $ragione= $obj->Ragione;
        $id= $obj->ID;

        // email 
        $account = array('email' => $email,
                    'kind' => 'admin#directory#member',
                    'role' => 'MEMBER',
                    'type' => 'USER');
        

        // set member
        $member= new Google_Service_Directory_Member($account);                        

        switch($action)
        {
            case 'ADD':
                $request = $service->members->insert($lista, $member);
                break;

            case 'DEL':
                $request = $service->members->delete($lista, $email);
                break;
        }

        // add to batch
        $batch->add($request, $id);
        
        // update
        if ($mode == 'TASK')
        {

            $sqlupd = "Update myTable set Process=1 where ID=".$id;
            $cmd = sqlsrv_query( $conn, $sqlupd);
        }
        
    }

    // run
    $results = $batch->execute();
    
    echo json_encode($results);
     
}else{
     die( print_r( sqlsrv_errors(), true));
}

ERROR

Fatal error: Uncaught Google_Service_Exception: Error 502 (Server Error)!!1
in C:\mypath\www\src\Google\Http\REST.php on line 118

What can be the problem?