As per IRCC, the last updated date now just means (and perhaps always did), when the data the tracker is showing you was last pulled from their system.
In my case this is actually relevant - the "Last Updated" date in the tracker was stuck at Nov xx 2022 for a long time (this was the case for many of us). In reality, they had actually started working on my Eligibility in Dec 2022, and completed it in Jan 2023, but the tracker still showed "Not Started".
Finally after the system update in January, my Eligibility in the tracker went from Not Started to Completed, and now in the history section it shows it went to "In Progress" actually back in December, but the tracker just wasn't showing that.