We have taken a fair number of cruises over the past 5 years and the only time this has happened was with P&O. We were charged for an amount my husband allegedly spent in the spa area in addition to an item from the mini bar, which we had not had. Anyone who knew DH would know the spa purchase was hilarious - he buys his toothpaste and deodorant from Lidl 😁. He didn't even known where the spa was let alone buy anything! I did get them to refund, but it took effort and the whole episode was very odd in my book.
Definitely worth checking as the OP says.