Unity PHP/SQL table creation adds strange characters to table name

I am using the following PHP code which takes in the tableName from Unity using the following c# function where the tableName is actually an email address. I can get the table created just fine, but it seems Unity and SQL have some sort of character/collation issue that I can't get past.

if the value of tableName is obtained from $_POST, it adds "​" to the end of the tableName. For instance the tableName "myemail@email.com_points" appears with the SQL tableName "myemail@email.com​_points". If I replace the $tableName variable in the below PHP code with a string rather than a $_POST variable, the table name appears correctly.

$tableName = $_POST['tableName']; <------ DOESN'T WORK $tableName = 'myemail@email.com_points'; <-------- WORKS

I have changed the character/collation of the database to UTF8_general_ci and to UTF8mb4_general_ci and just about every other suggestion I could find - and nothing works - not even renaming the table once it's been created. ANY advice would be much appreciated.

C# function:

 public void createPointsTable(string tableName)  
     {
 
         WWWForm data = new WWWForm ();
         data.AddField ("tableName", tableName);
 
         WWW www = new WWW (createPointsTableUrl, data);
     }

PHP code:

 <?php
 include_once('db.php');
  
 $tableName = $_POST['tableName'];
 
 $sql = "CREATE TABLE `$tableName` (id int NOT NULL AUTO_INCREMENT, kid varchar(255) NOT NULL, doy int NOT NULL, pointsChange int NOT NULL, reason varchar(255) NOT NULL, dailyPoints int NOT NULL, PRIMARY KEY(id), UNIQUE(id))";
 
 $result = mysqli_query($conn, $sql);
 
 if ($conn->query($sql) === TRUE) {
     echo "Table Created";
 } else {
     echo "Error: " . $sql . "<br>" . $conn->error;
 }
 
 $conn->close();
 ?>