I called to try out the Price Guarantee a couple of weeks ago, 3 separate times (different representative each time), with no luck each time.
They all quoted the "booked a cruise on or before March 31, 2022, on sailings between June 12, 2020 and September 30, 2022" from https://www.royalcaribbean.com/aus/en/faq/questions/best-price-guarantee-policy. Which is fair enough, as the cruise is in December.
I am guessing the only difference is if you went through a Travel Agent it looks like it is not a blocker - but if you booked directly through RC (which we did) no such luck...