One may assume that NCL might be tired of labor strikes at the port that happened in 2023. Such port closures for strikes also affect the availability of food and other supplies needed weekly.
What strikes are those? I live in the UK and haven't heard of them. The bread and butter of Portsmouth port's civil traffic (as opposed to military) is ferry traffic- which is why cruises use the ferry port as their terminal.
How many days were there strikes which closed the port? Did any of those affect NCL?
If ferry traffic had been disrupted like that, or indeed the cruise traffic, you would have thought it would have been widespread news. There has been some, I believe, limited disruption due to strikes at the French ports served from Portsmouth.
There are 78 cruise calls there this year- which does not suggest that other lines see a labour issue. That may sound a small number compared to Southampton, but historically is a very healthy number.
This is far more likely to be about wider fleet deployments.