I call a form with fancybox 2.1.5 which works fine on desktop view. But on any smartphone browser I get the message: "The requested content could not be loaded. Please try again later." The setup is:

    $(document).ready(function() {
    $(".various").fancybox({
        helpers: {
            overlay: {
                closeClick: true // default is true
            }
        },
        maxWidth    : 1200,
        maxHeight   : 800,
        fitToView   : false,
        width       : '80%',
        height      : '80%',
        autoSize    : false,
        closeClick  : false,
        openEffect  : 'elastic',
        closeEffect : 'none'
    });
});

The link looks like this:

<a class="various fancybox.ajax buttongreen" href="https://domain.tld/form.php">Contact form</a>

The server is running with php 8.0