To move Blog pagination prev/next above Comment box in Squarespace, you can use this code to Website Tools > Code Injection > Footer
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.1/jquery.min.js"></script>
<script>
jQuery(document).ready(function($){
$('section#itemPagination').insertBefore('section.blog-item-comments');
})
</script>
Result
