I contacted them proactively. The difference in price was exactly the difference between the "best available" rate for the points room and that rate for the room we booked. They sent a fairly old fashioned word document for me to sign agreeing to the upgrade fee, and they took a deposit of 30%, refundable until maybe 14 days out? But they said if we had to cancel our trip on short notice due to covid they would reschedule without penalty.