What are the potential pitfalls of using nested forms in PHP for pop-up windows?

Using nested forms in PHP for pop-up windows can lead to conflicts with form submission and data processing. To avoid this issue, it's recommended to use separate forms for each pop-up window to ensure data integrity and prevent unexpected behavior.

<!-- Popup window 1 -->
<form action="process_form1.php" method="post">
    <!-- Form fields for popup window 1 -->
    <input type="text" name="field1">
    <button type="submit">Submit</button>
</form>

<!-- Popup window 2 -->
<form action="process_form2.php" method="post">
    <!-- Form fields for popup window 2 -->
    <input type="text" name="field2">
    <button type="submit">Submit</button>
</form>