How to tamil font in export CSV file. we are facing ? error – Mysql

We are trying so many ways tamil content show like in csv file " தூதà¯à®¤à¯à®•à¯à®•à¯à®Ÿà® " please help me .

 mysqli_set_charset($db, "utf8mb4");
$query = $db->query("$reports");

if($query->num_rows > 0){
    $delimiter = ",";
    $filename = "report_" . date('Y-m-d') . ".csv";

    // Create a file pointer
    $f = fopen('php://memory', 'w');

    // Set column headers
    // $fields = array('ID', 'FIRST NAME', 'LAST NAME', 'EMAIL', 'GENDER', 'COUNTRY', 'CREATED', 'STATUS');
    $fields = array('Ticket No','Name','Phone','Zone','Ward','Street','Department','Category','Description','Asgn. Employee','Date','Overdue Date','Status Updated On','Status');

    fputcsv($f, $fields, $delimiter);

    // Output each row of the data, format line as csv and write to file pointer
    while($row = $query->fetch_assoc()){
        $count = 0 ;
        $status = ($row['status'] == 1)?'Active':'Inactive';
        $lineData = array($row['ticket_id'], $row['empname'], $row['COMP_MOB'], $row['zone_name'], $row['ward_name'],$row['ASSN_STREET'], $row['name'], $row['complaint_cat_name'], $row['DEPT_DESCRIPTION'], $row['emp_name'],$row['dateofsubmit'],$row['overdue'],$row['dateofupdate'],$row['STATUS']);
        fputcsv($f, $lineData, $delimiter);
    }

    // Move back to beginning of file
    fseek($f, 0);

    // Set headers to download file rather than displayed
 header('Content-Type: text/csv');
 header('Content-Encoding: UTF-8');
  
    header('Content-Disposition: attachment; filename="' . $filename . '";');
    //output all remaining data on a file pointer

    fpassthru($f);
}
exit;
?>

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After export csv we need tamil font