Some Royal Caribbean policies tend not to be enforced consistently, but it looks like things may be changing with the wine you bring onboard.

Royal Caribbean allows its passengers to bring bottles of wine onto its ships, but the corkage fee that is supposed to be applied has largely been ignored for many years.
That could be changing now.

The official policy states guests can bring up to one bottle of wine per adult on embarkation day onto the ship. If that wine is opened in a bar, restaurant, or lounge, then it's subject to a $15 corkage fee.
The wine you bring onboard must be carried on and not put in your checked luggage.
In reality, that corkage fee has rarely been enforced. It's been my experience that the crew member will open it and not say anything.

However, reports are popping up of stickers being added to wine bottles to indicate if the corkage fee has been waived or not.
This applies to wine with twist tops, as the corkage fee is more a fee for bringing your own wine rather than the actual mechanics of opening it.
New stickers

A number of cruisers who have gotten bottles of wine gifted onboard the ship are reporting stickers on their bottles.
Pattycruise wrote on the Royal Caribbean Blog message boards, "I just saw another photo from a group I’m in that said corkage fee waived on the sticker."
These stickers are appearing on bottles of wine that passengers receive from Crown and Anchor Society or Casino Royale as an incentive for their loyalty.
Enforcing an old rule

What cruisers needs to be aware of is they may be charged for wine they bring onboard.
What this means is if you're someone that has been bringing bottles of wine on your cruise and skated by without paying the corkage fee, this could be changing.
Essentially, the policy hasn't changed at all, but it may now be enforced. That could be confusing to someone who wasn't aware of the corkage fee being applied before.

If you buy a bottle of wine on your cruise ship, there is no corkage fee.
After a bottle of wine is opened for you, you can either take any unfinished wine in the bottle with you or have it stored for you to be used on another day and time.

It's quite convenient to have your bottle opened in the Main Dining Room, have the crew store it, and enjoy the rest on another day in the same or a different restaurant.
The crew marks your name and stateroom number on the bottle, and any crew member around the ship can retrieve it to serve you elsewhere.
You can still open your wine on your own

One way to get around the corkage fee is to open the wine and keep it in your cabin.
The corkage fee is for wine that's opened in public venue onboard, but there's no such application if you have it in your room.
In fact, your stateroom attendant can provide a wine opener upon request for no fee.
You could enjoy the wine in your cabin, or opt to take a glass with you around the ship. In either of those scenarios, there would be no fee.
Bringing your own wine is a great way to save money

One of the oldest hacks for saving money is to bring your own bottle of wine.
Not only will you pay less for wine if you buy it retail while at home, but you'll have a far greater selection of choices.
Even with the corkage fee, you'll probably come out ahead with your own bottle of wine than buying a bottle onboard the ship because of the markup with wine offered for sale by Royal Caribbean.
Tips for bringing your own wine (and not ending up with a broken bottle)

Bringing your own bottle of wine can save you money, but no one wants to end up with a bottle that breaks.
Instead of buying the bottle of wine at home, you could wait to buy it at your embarkation city. This avoids packing a bottle in your luggage and hoping it doesn't break during transit.
Not only could you buy it at a store near your hotel, but you could leverage a shopping app like UberEats and have it delivered to your hotel.

If you are going to pack your own wine, a wine diaper could do the trick (this is an affiliate link that costs you nothing extra to use). These are reusable, protective and absorbent wine bottle bags designed for traveling.
If you prefer a DIY approach, try putting your wine in a 1.5 gallon ziplock bag and pad the wine with clothing around it, such as socks.