To my knowledge, disabling the browser back button specifically within a Power Pages Basic Form is not directly possible.
However, there are some alternative approaches you can consider like using Custom Javascript: You can add custom JavaScript to your Power Pages to manipulate browser behavior. For instance, you could use JavaScript to override the default behavior of the browser back button.
<script type="text/javascript">
// Prevent the user from navigating back
window.history.forward();
// Optional: Display a custom message when the user tries to navigate back
function noBack() {
window.history.forward();
}
</script>
