What is the potential issue with the form not submitting variables in the provided PHP code?

The potential issue with the form not submitting variables in the provided PHP code could be due to the method attribute in the form tag being set to "get" instead of "post". When using the "get" method, form data is appended to the URL as query parameters, which may not work correctly if the data is too large or contains special characters. To solve this issue, change the method attribute in the form tag to "post".

<form method="post" action="process_form.php">
    <!-- form fields here -->
</form>