I am arriving on the 21st of October 2021. I have to apply for the COE, but chances are the quarantine for fully vaccinated is lifted then, or perhaps shorter (7days?). I understand from the application that the ASQ hotel has to be booked and fully paid. Do I lose my money when quarantine is no longer required?
Yes, you will probably lose your money if there is some overlap.
However, the quarantine has been reduced to 7 days beginning October 1. So it should be a good idea to talk to the hotel if you already paid, to get some refund.