From Royal's website:
The following policy applies to sailings that were cancelled as part of our COVID-19 operations suspension:
You will receive one Future Cruise Credit combining the two amounts: 100% of your original Future Cruise Credit amount and 125% of any additional cruise fare funds paid on the reservation. The additional 25% issued as an FCC can be redeemed on any sailing departing on or before December 31, 2022 or one year from the original sailing date, whichever is later. The remaining FCC amount will not have an expiration date.
So, it looks like at least the original amount paid will not expire, only the additional 25% added on.