One of the things I heard going into the movie was "it goes really off the rails in the final act." And then I spent the entire movie up to that point wondering "Is this... on the rails?" If anything, I thought the ending was the least odd!
It's funny that I can simultaneously agree with you that it was brilliant and have very little desire to see it again in the near future. I guess that's an achievement in its own right though. Lanthimos certainly knows what he's doing. Thanks for reading and for the kind words, R.J,