Based on your settings, a code of Alumni Parent is added to the Parent record when a student graduates, it comes into RE on the Parent record with a start date according to how they have their Connect RE configured. End date is blank as they are considered a current Parent of Alumni there is no further end date functionality through the integration to mark an end date.
This code was added due to a change on the Student, now Alumni record. Meaning the change on the Alumni record is what triggered the Constituent Code of Alumni Parent to be added to the Parent record in RE.
If a change is made to the end date on your side for this code that is synced through the integration:
If a change is subsequently made on the Alumni record in your ON product that syncs through the Integration, which in this case was an Address change; This now makes the Alumni Parent an eligible record as far as the Constituent Code is concerned through the integration.
The integration will check to see if the Alumni Parent code is present on the Parent record in RE and/or look at the values in the Constituent Code in RE and re-sync accordingly. A change to the end date in RE , would subsequently be blanked out.
If the Constituent Code had been removed , it would then be added to the Parent record again.
Essentially it's checking to see if the Constituent Code has the same values as when it was originally added, otherwise syncs a change to make it match how it's supposed to be through the integration. Seems a bit counter intuitive considering the change is made to the Alumni record, but if you think of it in terms of how this code was originally added to the Parent record , due to a change in the Education Status status of the Student , makes a bit more sense that it does a re-check of the Code through the integration.
While deceased is a field that syncs independently from the Constituent Code, the integration doesn't incorporate this into end dates. An end date could be added manually, or by part of some functionality in RE as it pertains to someone who is now deceased. However, a change in the ON product could then blank the field out again at a later date.