Decision Made (on the old
ECAS status tool) is equivalent to having all sections complete except oath (on the
new citizenship tracker). So no, you won't see any other change to DM on the new tracker, the next update will be the oath invite/date. If you were to login to the old ECAS tool and check it now, it should show DM if all your sections on the new tracker are complete (except oath).
Up until last year the only way to check your application status was using the ECAS tracker, which only shows the major changes i.e application received, in process, any communications sent and decision made. Back then you'd have to rely on GCMS notes to get a detailed picture of the status of specific sections. It's good that they now introduced this new one.