Incorrect shader Effect On Changing Render Scale

I was Trying To Create A force field Effect (https://youtu.be/NiOGWZXBg4Y) but it works incorrectly on changing the render scale. Would Appreciate Any Solutions https://drive.google.com/file/d/1R-agkr2xLLbF7KbBDWZnnBfA6xZ7JFF5/view?usp=sharing --> shader screen shot.