Just off the Discovery. I tried to reply while onboaed, but I think the wifi ate it.
I had dinner in the Crown Grill my first night...not through any great planning on my part, but because I'd had to cancel due to Covid, rescheduled within 9 days of departure, and that was the only night I could get a reservation.
I *did* get the free bottle of wine. Details follow.
The coupon was in a book of coupons emailed to me directly from Princess. The subject line is, "Res. #xxxxx, Your Exclusive Coupon Book is Here".
I had to reserve directly with Princess to keep my discount, and it says that the coupon book is from the Princess Travel Advisor, so maybe it is only for booking direct? Or only with the Premier Beverage Package? Or both??
This was my second Princess Cruise in 10 years and I was in a Guarantee Inside cabin, so nothing to do with Loyalty Status or cabin class. I wasn't given a bottle out of the kindness of their hearts. I had to request it and explain the offer.
Anyway, I asked my waiter about the coupon and offered to show a screenshot. I also explained that it was for one of the day's Featured Wines and that I wasn't trying to get a free bottle of something fancy. He had to go speak with the manager, but came back to say yes. They never did ask for the screenshot. There were 2 options for which wine, and I went with his recommendation. I asked if I could take the bottle back to my room, and they said that was fine.
I had brought a bottle of supermarket sauvignon blanc, and I also won a bottle of "champagne" in one of the trivia contests, so I ended up with White Plonk, Red Plonk, and Bubbling Plonk!
TL;DR- I did get the free bottle, it's not a myth. I asked nicely and offered documentation.