Just off Nautica last week, and yes the walls are definitely not as magnetic as they were pre-Next.
I tested them lol and here's what I found in our C1 (deluxe ocean view) on deck 4:
Highly magnetic: door to corridor, outside (porthole) wall, frame of mirror at desk, ceiling
Pretty/moderately magnetic: bath door, wall opposite the desk (the wall the headboard is on)
Not very/not at all magnetic: wall in cabin around bathroom, wall on the desk side, closet doors, desk
For example, my neodymium hooks held a ball cap or light rain jacket on the outside of the bath door (pretty/moderately magnetic), but not a heavy jacket.