Passing mesh scale from World to Screen

Hello, I can't get the quads' size right in the shader. I pass the quads' localScale to the shader after applying WorldToScreenPoint to it. Is it the right way to transform scale from World to Screen space? I also divide it by _ScreenParams.xy in the shader. Is it correct?

In the Screen, the scale remains dependent from the screen size. As you can see I got the image right (the first one) according to the quads' scaling, but whenever I resize the Game View I get the error shown in the second image.