I’m on this same sailing and will share my experience as my cabin was also arbitrarily changed, although under different circumstances.
i prefer larger balconies than the standard balconies on the Royal class, so I booked one of the 10 “deluxe obstructed” balconies at the front of Emerald. They have larger balconies , and since they taper down in size toward the bow, I chose the furthest one back on the starboard side, my preferred side. I think all 10 were available at time of choosing.
My reservation was marked no upgrade, though my change was not an upgrade.
At some point, don’t remember if it was before or after final payment, I noticed my cabin had been moved from starboard to port side, and one cabin closer to the bow, thus a little smaller balcony. Still, larger than standard, but I lost a few square feet of balcony real estate. Curiously, they didn’t move me to the corresponding port balcony which was still available to book.
No notice from Princess of the move, and if the (big box) TA was notified, they didn’t pass it along.
Now I could have raised a stink right then, but I had put in a bid for an upgrade to a non-obstructed premium deluxe balcony, which were still plentiful, so I figured, if I get one of those, (and I put in an above minimum bid), it would be a moot point anyway.
Long story shorter, I did not win my upgrade bid, and ended up in a smaller balcony cabin for some unknown reason.
it wasn’t a big enough deal to get worked up over, but would have certainly liked to know why I was arbitrarily moved.
i may never get an explanation, but it was very puzzling and certainly annoying.