When Scenic first went over to all inclusive yes I’m old enough to remember that, they frowned on extra tipping (tipping is part of all inclusive) now it’s not remarked on so if you think a member of the crew be it hotel or maritime goes above and beyond go ahead. If I’m right and not out of date there is a German company that trains the majority of cruise staff for many of the companies. It had two departments, maritime and hotel. When the companies recruited their staff they were then trained to that companies standards.
I’ve known crew to either refuse tips or thank gracefully and ask if it’s okay to add to the end of season pot.
Tipping is so subjective easy to work out in the U.K. just ask if it goes to the staff etc. Its also straightforward in the US, slightly more difficult in Canada and the rest of Europe.