Light Yagami's actions in the Death Note world significantly disrupt the balance of power. By using the Death Note to eliminate criminals and those he deems as obstacles to his vision of a utopian society, Light takes on the role of judge, jury, and executioner. This results in a shift of power dynamics as he becomes a central figure with the ability to control life and death. The presence of the Death Note itself challenges the existing power structures, leading to a complex web of manipulation, deceit, and consequences that ultimately impact the balance of power within the Death Note world.