PHP code on display when input data is executed

Question

I have been trying a few exercises for revision and I am having issues with a piece of PHP code - a small form / submit into a database - when I submit, the execution is not working as intended (it should state "Success!" or atleast "Error":

    <?php  
    $servername = "localhost";  
    $username = "username";  
    $password = "password";  
    $dbname ="whatdo"; 
    
    $conn = new mysqli($servername, $username, $password, $dbname); 
     
    if ($conn->connect_error) {
        die("Connection failed: " .$conn->connect_error);
    }
    
    $disc = $_POST["disc"];
    
    $sql = "INSERT INTO whatdo (disc) VALUES ('$disc')";
    
    if($conn->query($sql) === TRUE) {
        echo "Success!";
    } 
    else {
      echo "Error: " . $sql . "<br>" . $conn->error;
    }
    
    $conn->close(); 
    
    ?>

When submitted, the page displays the following:

    connect_error) { die("Connection failed: " .$conn->connect_error); } $disc = $_POST["disc"]; $sql = "INSERT INTO whatdo (disc) VALUES ('$disc')"; if($conn->query($sql) === TRUE) { echo "Success!"; } else { echo "Error: " . $sql . "
    " . $conn->error; } $conn->close(); ?>

I thought I had all my bases covered but I have obviously missed something obvious.