So I don't know about your mobile device but I see that there are what, webp extension? My device won't play/show it, but it will support "downloading" it... That I'm afraid has nothing to do with the template, responsive or otherwise. No idea why that filetype was selected, but highly suggest using something more web browser friendly...

As far as any other "issues"? I don't really see anything directly on the site in a mobile device that is problematic per se. Nothing that would make me want to avoid the site if it contains the things I were searching...