When you have a full grid and you buy some "+1" power with a star, it's called "Overpower grid" and it says :
"Your Power Grid is full. Additional Power will permanently upgrade your Grid Defense" which I understand.
But it also says: "The bonus will decrease the higher your Grid Defense gets, to a maximum of +25", what does this mean? What will decrease exactly? How can it reach a "maximum" when it's "decreasing"? Is it a typo?