I have not cruised since prior to Covid, but we are getting ready to cruise again with our kids in about 30 days. I do not believe this is correct. Carnival has a dedicated section on their website about "under 2s" and activities in Camp Ocean. From what I understand, everything for under 2s is at an hourly fee if you want to leave them in camp by themselves on port days. Check these things out:
https://help.carnival.com/app/answers/detail/a_id/1077/~/camp-ocean-infants-under-2%3A-things-to-know
I will report back after our return in early November about what I learned/experienced as we are cruising with 3 kids: 17mos, 4yrs, and 6yrs.