That "cut" happened before they even started working on the show. Despite the original thought of 5 seasons, it was essentially planned for 2 seasons right from the start.
From Gilroy’s own telling, it happened during the filming of Season 1 in Scotland? That seems to be what he told Happy Sad Confused on their recent interview.
He realised that everything, absolutely everything in Star Wars needs to be designed, that it took ages to do, and that it would be forever to make 5 seasons. So he pitched to Diego to only make one more.
