php is inserting empty data in mysql database automatically everyday

Question

I have created an application where user can send notification to other devices with php as backend and fcm notification. On successfully sending the notification it store the details of notification and notification sender(user) on mysql database with table name 'notification' and 'sender_details'. However, new empty data are being stored in these two table everyday while the app is not even opened by anybody. Please Help

<?php
include('../conn.php');
$api_key="xxx";
    
    $url="https://fcm.googleapis.com/fcm/send";
    $fields=json_encode(array('to'=>$to,'notification'=>$data));

    // Generated by curl-to-PHP: http://incarnate.github.io/curl-to-php/
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, ($fields));

    $headers = array();
    $headers[] = 'Authorization: key ='.$api_key;
    $headers[] = 'Content-Type: application/json';
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

    $result = curl_exec($ch);
    if (curl_errno($ch)) {
        echo 'Error:' . curl_error($ch);
    }
    curl_close($ch);
}

//fetching data
if (!$conn) {
  die("Connection failed: " . mysqli_connect_error());
}

$date3 = date('Y-m-d');

  $sqlm = "SELECT dateonly FROM user_details WHERE token='".$_POST['token']."' AND dateonly='$date3'";

$result3 = mysqli_query($conn, $sqlm);
        if (mysqli_num_rows($result3) > 0) {  
              echo "alreadysend";
          }else{
 
$sql = "SELECT * FROM data WHERE group='".$_POST['group']."'";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {  
  // output data of each row
  while($row = mysqli_fetch_assoc($result)) {
      
       
      $to=$row["token"];
      
      //for sending email
       $email=$row["email"];
      
      
      
     
    $time2=date_default_timezone_set('Asia/Katmandu');
$date2 = date('Y-m-d h:i:s a', time());



      $sql2 = "INSERT INTO user_details (name, phone, city)
VALUES ('".$_POST['name']."', '".$_POST['phone']."', '".$_POST['city']."')";
      
      if ($conn->query($sql2) === TRUE) {
           echo "New record created successfully";
} else {
          
  echo "Error: " . $sql2 . "<br>" . $conn->error;
}
 
//end of second sql queries
      // 2. for body of message
      
           $body = $_POST["name"].' needs ' at '.$_POST["city"].', '.$_POST["hospital"].' hospital. Contact on the following number: '.$_POST["phone"].' (Message from them: '.$_POST["message"].')';

      // 3. for title
        $title = New Notification';
      
$data=array(
    'title'=> $title,
    'body'=>$body,
      'image' => $img,
        'vibrate'   => 1
);

      $time=date_default_timezone_set('Asia/Katmandu');
$date = date('Y-m-d h:i:s a', time());

 $dateonly = date('Y-m-d');
     
      $sql3 = "INSERT INTO notifications (title, body, time, dateonly)
VALUES ('$title', '$body', '$date', '$dateonly')";
      
      if ($conn->query($sql3) === TRUE) {
           echo "New record created successfully";
} else {
          
  echo "Error: " . $sql3 . "<br>" . $conn->error;
}
 
//end of third sql queries 
      

notify($to,$data);      
      
     
  }
  
  
  
  } else {
  echo "noresults";
}


}
         
 
mysqli_close($conn);

?>

All the post data are being received from the app