I see that effective Aug 01 Venice will not be allowing large cruise ships toi port there. That will force some itinerary changes. I see that NCL had plans to port the Gem there in 2022 but that will obviously need to change unless they do everything via tender or a new port outside the city would need to be opened. According to the below article, the ban applies to ships weighing more than 25,000 tons or longer than 180 meters (530 feet).
Smallest NCL ship (Spirit) is 75,904 ton and 268 meters (884 feet)
Smallest RCL ship is Grandeur at 73,000 ton
Smallest Carnival ship is Ecstacy at 70,000 ton