Undefined offset 0 in system check for custom fields after upgrade to 5.23
Line 109 in CRM/Utils/Check/Component/Schema.php. I think this might be a similar issue to #1555 (closed), where for whatever reason the smart groups have a different format and there is no
form_values. The fix/workaround for that was https://github.com/civicrm/civicrm-core/pull/16417.
So this seems related to #1471 and https://github.com/civicrm/civicrm-core/pull/16267
I only see the errors when I first log in, or log out and then back in. They happen on the system status check screen but you don't see them because they get snippet'd out, but they're in drupal watchdog.
Tentatively marking regression although it's just a status check E_NOTICE. Will take a closer look.