I think I can confirm what has already been said over and over here. As for topless, some have done it on upper decks, but it is usually very windy and uncomfortable to be there. There are always people exploring the ship ("legit" or not), so that is probably another reason women would probably not be topless.
As for nude or clothing optional, those days on America sailings are over, except for charter/takeover cruises. Whether the reason be society's snowflakes that get butt-hurt about everything or the fact that many of the popular water slides are elevated to a point where kids and other could easily see those deck areas - who knows? You might find topless on European sailings here and there. AIDA is a German cruise line which still has a C/O sundeck. Note: Much of the information regarding C/O resorts and destinations you may find is out of date. Do not go by the thing you find on the internet.
I have heard the Quest show on some cruises has gotten a bit out of hand (ie: fun). But as others have said, that is clearly denoted as 'adult' in the Cruise Compass. It is a blast and not to be missed!
Sorry for good news or bad news. Depends on your point of view 😉
~Bob and Joelie~