Here’s what I got after deleting the db.php link and activation of the Query Monitor plugin (((
Fatal error: Cannot declare class ComposerAutoloaderInit9bc748a33ab984c092a749a74d7b8261, because the name is already in use in?/var/www/…/data/www/…/data/plugins/query-monitor/vendor/composer/autoload_real.php?on line?5