I checked my account and it was deducting points according to the rules. May I suggest that you take a snapshot or print screen of or just write down all the numbers and dates from the Transaction Menu "Points Expiration" before you do any redemption? Then do the same and compare after Redemption. It will either put your mind to rest that all is working well or it will give you a proof which will help AARP looking into the problem. Hope all works out well!
The earned points expire in 1 year if not used, and redemption points are subtracted from the oldest points earned. Under the Transaction History, there is a drop down option to see how many points will expire each month from the previous year (2020), and a "warning" to redeem those points before they expire. The system appears to be working as it should. I have been keeping track, and my "older" points are being subtracted that were earned in 2020.