@Brian-J-1 Changes made after a booking is confirmed, cannot be applied to those bookings, it will only be applied to future reservations.
This one of those things a host just has to eat and consider it part of the learning curve. Trying to add an extra charge that wasn't mentioned when they booked, to a confirmed reservation, isn't fair to the guest and will quite reasonably make them angry and likely report you to Airbnb.
The cleaning fee you have now added will be automatically applied to future reservations and the guests will see that in the breakdown of what they are being charged in total.