Why is Preussen receiving a nerf? (Campaign ship)

In the latest patch notes it says that Preussen will receive a nerf, my question is why?

I thought campaign ships don’t receive nerfs? Buffs sure, but nerfs have never been a thing for them?

I’m just wondering because they said “they will continue to monitor Legendary tier ships” is this just a thing for legendary ships that might be introduced through the campaign?

Or is this going to open the flood gates for future campaign ships to receive nerfs because they might be “OP”?

Either way Preussen does deserve that nerf.