If you place a crescendo that ends with a dynamic mark on the last note, Dorico assumes that it lasts until the first beat of the next measure and adds a measure to the end of the piece. The workaround is to cut the last note short with a short rest before the barline.
Yeah, I know, and I don’t like the automatic behavior. But there’s a much easier way. Click on the last dynamic mark and press Shift-Alt-Left arrow once. It’ll shorten it by one rhythmic grid unit. Set your rhythmic grid small and the difference won’t be noticeable, but it will drop the last extra bar.
Excellent