Well if you were 20lbs heavier and are eating the same now as you were then, youd have to lower cals to keep up w the sane pace of weight loss. Calories are a unit of energy and the less you weigh the less energy it takes to move your body through out the day therefore requiring lesser calorie intake to burn off fat, given your macros are correct to preserve muscle.

At the same time, your metabolism adjusts to extreme calorie deficit to avoid starvation at all costs slowing or halting fat loss