While not mentioned in the release note, I think some improvements were made to the ERG algorithm. It is especially apparent when doing short intervals.
I was doing my normal 40/20 workout tonight it nearly ripped my legs off! The “old” ERG mode would undershoot for 15 seconds and gradually adjust. The “new” mode tends to overshoot but adjusts ALOT quicker. The resulting 40 second interval is alot closet to target.