We are upper tier D+ so we have been on quite a lot of RC cruises. We are also stockholders .
We definitely see a decrease in everything on the Royal cruises including food quality & variety, entertainment quality, and quantity of staff onboard.
On our Jewel cruise a few months ago we decided to look at other cruises out of the NYC market. We booked a January cruise on Carnival Venezia and just got back.
The food quality was better in the MDR for both breakfast and dinner. The food in the buffet for breakfast was horrible. For lunch it was about the same as Windjammer except it had a deli in the buffet that was good. The baked goods in the Carnival buffet were light-years over Royal's gelatinous desserts. The Carnival buffet desserts were bakery quality and Royals is school cafeterias.
A huge advantage to Carnival was their free stand along food operations outside the buffet. A pizza stand made excellent personal pizzas, on sea days the seafood restaurant serves good Chinese food for lunch. There is a Mexican operation that also serves Italian sandwiches and finally a Guy Fieri's Burgers that served some of the best burgers I've ever eaten.
The design of the Carnival Venezia was horrible and nowhere nearly as functional as Royal's ships but the food was much better.
So when deciding on cruises I will now consider Carnival whereas I rarely have gone on them.