Looks like some debug output showing up in the question list admin

The add_column function in core/admin.php does print_r($columns); which causes some junk to be output into the question list in the backend. Easy enough to delete that line, but wanted you to know so future updates wont make it return

Not sure when this started showing up, but it has not always been there even though the print_r code has been there for a long time. Maybe something changed in the WP core to cause it to be visible where before it was suppressed somehow?