Sport mode is getting better gas mileage than regular

I have a 2022 Ford escape I commute an hour in the mornings on the highway. I have instantaneous fuel mileage on the dash. With cruise control on going the exact same speeds sport mode is getting at least three more kilometres per litre(often times a lot more). I’ve tried to look this up and people say it’s because of acceleration, but I could change between modes while in cruise, and the mileage will instantly improve according to this instant instantaneous mileage. The most I can think is it has something to do with cylinder deactivation and gearing ratios.