It seems ALL hotel loyalty programs have done this kind of "adjustment" without notifying the member.

I now make periodic screen shots of all programs just so I have a Static record.

On a somewhat related matter - HHonor is the worst program in the way how it shows the balance. While you can have monthly email sent to you to show the balance at the time, the number is NOT "frozen" in time - i.e. the number will change as your activities in subsequent months cause the balance changes, and the number in previous emails ALSO change to the latest. How stupid this is!
The HH's subtraction of award redemption and the actual posting also is a duplicate entry, often cause huge confusion esp when the award stay is months away, thus not showing on the same page of the initial deduction at booking. It is so bad, HH is the only program I create a spreadsheet to keep track of the movement.