Can someone help me with the possible scenario here?

I have purchased an eco flex ticket, multi city one way, upgrading the 2nd leg with points to business in Dec 2022.
Say for example I had to change dates, can they pick new dates based on my existing class of travel OR will they 'return' the points?
The spanner here is that the points were expiring by the end of June 2022 - so does that mean I will my points which I used to upgrade (as if they 'return' the points it will have attributed the same expiry date right?)