@Amanda1713 The guest's reservation details will show the original rules and checkout times that were in place when they booked. These comprise part of the contract they agreed to at the time of booking, so if at all possible, you should honor those terms for these guests rather than the new ones.
If you're unable to honor the original terms/times and it might affect the guest's stay, the done thing would be to notify them and offer a full refund if they decide the booking is no longer suitable.