Upgrader task needed to support start-date feature
5.40.2 + GC 1.11.0 gave an error "Warning: Invalid argument supplied for foreach() in /home/x/public_html/media/civicrm/ext/uk.artfulrobot.civicrm.gocardless/CRM/GoCardlessUtils.php on line 526". This was fixed by going to the admin › contribute » gc settings page and saving. (mattermost ref)