if there is anti gravity it gets more strong as it travels for the same reason why all forces get more strong as they travel
if there is anti gravity it creates repulsion only for a certain distance
gravity gets more strong as it travels for a lot of reasons - gravitons influence time and space like help time and space have a shape - gravitons influence the vacuum and because of this gravitons get more energy - gravitons create attraction for positive energy particles to conserve energy and momentum gravtions get more energy and momentum
gravitational waves get more strong as they travel for the same kind of reasons that gravitons get more energy as they travel
https://www.youtube.com/watch?v=6q2njtqa5Wo
Kurt Stocklmeir