What happens when an old order that was completed but the gets refunded and How does the plugin handle the points that were received from the refunded order?

There are total two ways for handling the refund request.

1- Earn Points

Product Assigned Points: When user make a refund request of that product which have some of the assigned points then after refunding the amount, the earned points will be deducted from his/her account.

Per $ Spent Point: When user make a refund request for an order from which he/she earned some of the points, then after refunding the amount, earned points will be deducted from his/her account.

2-Deduct Points:

Product Purchase through Points: When customer makes any refund request for that product which has been purchased free of cost(by using his/her points) then after refund request, deducted points will be refunded to his/her account.