My understanding is that thank you points are added to one's account and available for use the date the statement is finalized (and not until after payment)

I may book a rather expensive hotel stay on expedia that is refundable for months to come. Because of 3x bonus points I'd get this could wind up giving me 15-20k thank you points.

What happens if I spend these thank you points and then later cancel the pre-paid, refundable hotel stay. Would I just have a negative thank you points balance?