Ghost update or 'GU' - forum speak to be honest lol
It's when something on your account profile changes, perhaps wording or biometrics number/date is updated. Not a significant update like one of the steps - in process to complete or request letter for example (which would be accompanied by an official email).
It's a belief that when an 'agent' apparently logs in or 'touches' your account for whatever reason, mysterious ghost updates happen


Try not to stress over all the details and fear, it's out of our hands. I'm confident they are working as hard as possible to get our applications finalized ASAP.