Replace event title heading from <h3> to <h1> on pages with the "page-template-default" class.

Replace header tags.php

function my_swap_event_heading_js() {
    ?>
    <script>
    document.addEventListener('DOMContentLoaded', function() {
        // Check if the body contains the "page-template-default" class.
        if ( document.body.classList.contains('page-template-default') ) {
            // Select all event title elements by the specific class.
            var titles = document.querySelectorAll('.tribe-events-pro-photo__event-title');
            titles.forEach(function(title) {
                // If the element is an H3, replace it with an H1.
                if ( title.tagName.toLowerCase() === 'h3' ) {
                    var newHeading = document.createElement('h1');
                    newHeading.className = title.className;
                    newHeading.innerHTML = title.innerHTML;
                    title.parentNode.replaceChild(newHeading, title);
                }
            });
        }
    });
    </script>
    <?php
}
add_action( 'wp_footer', 'my_swap_event_heading_js' );