Quick Answer
All-purpose flour does not use the same grams-to-cups value as every other ingredient. Using a practical US cup reference, 125 grams of all-purpose flour is about 1 cup.
That means 100 grams of all-purpose flour is about 0.8 cups, while 200 grams is about 1.6 cups.
Flour compacts easily, so spooning and leveling is more consistent than scooping straight from the bag.