Judging by the number of ob_start() in that code, I’d say they’re doing some search-and-replace in the webpage, and replacing text they shouldn’t — like adding HTML meta tags in meta tag values — that’s a big no-no.
events-manager/admin/em-docs.php: ob_start();
events-manager/admin/em-options.php: ob_start();
events-manager/classes/em-booking.php: ob_start();
events-manager/classes/em-booking.php: ob_start();
events-manager/classes/em-booking.php: ob_start();
events-manager/classes/em-calendar.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event.php: ob_start();
events-manager/classes/em-event-post.php: ob_start();
events-manager/classes/em-events.php: ob_start();
events-manager/classes/em-location.php: ob_start();
events-manager/classes/em-location-post.php: ob_start();
events-manager/classes/em-person.php: ob_start();
events-manager/classes/em-taxonomy-frontend.php: ob_start();
events-manager/classes/em-ticket-booking.php: ob_start();
events-manager/classes/em-ticket.php: ob_start();
events-manager/templates/placeholders/bookingbutton.php: ob_start();
events-manager/em-actions.php: ob_start();
events-manager/em-actions.php: ob_start();
events-manager/em-actions.php: ob_start();
events-manager/em-actions.php: ob_start();
events-manager/em-actions.php: ob_start();
events-manager/em-events.php: ob_start();
events-manager/em-functions.php: ob_start();
events-manager/em-rss.php: ob_start();
events-manager/em-shortcode.php: ob_start();
events-manager/em-shortcode.php: ob_start();
events-manager/em-shortcode.php: ob_start();
events-manager/em-shortcode.php: ob_start();
events-manager/em-shortcode.php: ob_start();
events-manager/em-shortcode.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/em-template-tags.php: ob_start();
events-manager/events-manager.php: ob_start();
events-manager/events-manager.php: ob_start();
js.