I have also seen this change even mid cruise (my guess is someone complained to guest services about people cheating because they didn't win). I run enough WhatApp Group chats for sailings to think it is better to just swap and save all the finger pointing. Phones face down on table (or in a bag) and swapping seems to help.
The thing I HATED was in Sept on the Fantasy every trivia they made us hold up our phones and list all the ways we would not cheat including apps (or websites Im still not sure) I had never even heard of. It was a giant thing each time (not a quick simple dont cheat, dont use the internet, Mickey is watching like normal). I would much rather save the big speech and just say don't use the internet and then swap papers.