More like overbooked. The cruise lines are booked out to 2023 with those who had to cancel this past year.
CDC will only allow 33% capacity on the cruises. Those who are overbooked will have to bid on the available berths.
Also the CDC may renig on their promises, given the Indian strain and issues with it. Once that shows up, it will likely cut through those who had the mRNA vaccines (Get J+J or Novavax).
Best to wait until 2024 to cruise right now.