1.8 kg! If that's accurate it explains why these cars are so heavy.
If that piece was indeed 1.8 kgs, then it was primarily because of added ballast in order to optimize the weight balance of the car, and help it to comply to the rules about the mandated weight distribution figures.
And I learned the following a few days ago at this forum: putting at the outer edge of the front wing instead of in the senter part is in order to shift the left-right balance of the car. Certain tracks favour a car with a weight bias to one side.
Also, just for example: I found out today that the batterey on the F1 cars are limited to a minimum of 20 and a maximum of 25 kgs.
Off-Topic: about this left-right bias, the most extreme applications of that can be seen at Indy. the charismatic Indy Roadsters of the 50's and early sixties had the majoiry of the weight restin on the inside tires. Primarily in order to reduce the tire wear on the outside tires at the highspeed oval.
Certain F1 tracks might indeed be suitable for using the similar principles though nowher near as extreme as at Indy.