2. The reason for the decrease in points may be that you used points to exchange gifts.

3. If the gift has not been redeemed, whether there is a refund transaction on the credit card, the points will be returned when the gift is refunded.

4. Another possibility is that the points of this card you handle have special rights, such as airline co-branded cards, and the points of such cards will be automatically converted into mileage points of the corresponding airlines at a certain proportion at a specified time every month.

At present, all I can think of are these possibilities. If none of them are available, you can call the customer service hotline, and the customer service can check the points details.