dbconnect.php in wordpress root

I discovered that there is a file dbconnect.php in my wordpress root. This obviously shouldnt be there, unless it belongs to some plugin, or something. The header is like this:

/** Adminer - Compact database management
* @link https://www.adminer.org/
* @author Jakub Vrana, https://www.vrana.cz/
* @copyright 2007 Jakub Vrana
* @license https://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
* @license https://www.gnu.org/licenses/gpl-2.0.html GNU General Public License, version 2 (one or other)
* @version 3.6.3
*/error_reporting(6135);$nc=!ereg('^(unsafe_raw)?$',ini_get("filter.default"));if($nc||ini_get("filter.default_flags")){foreach(array('_GET','_POST','_COOKIE','_SERVER')as$W){$sg=filter_input_array(constant("INPUT$W"),FILTER_UNSAFE_RAW);if($sg)$$W=$sg;}}if(function_exists("mb_internal_encoding"))mb_internal_encoding("8bit");if(isset($_GET["file"])){if($_SERVER["HTTP_IF_MODIFIED_SINCE"]){header("HTTP/1.1 304 Not Modified");exit;}header("Expires: ".gmdate("D, d M Y H:i:s",time()+365*24*60*60)." GMT");header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");if($_GET["file"]=="favicon.ico"){header("Content-Type: image/x-icon");echo

I find a link from the author at https://www.vrana.cz/ to the plugin Inpsyde, who has created the plugin BackWPup, which is a good plugin that I frequently use. This is a multisite installation. But still this seems more than odd to me that this file should reside in wordpress root?