We don't want a constant spawn rate, we need a burst. In the Spawn node of the VFX. Add a single burst component. Parametrize the amount of particles it will spawn. Parametrize the delay, this will be ...

So Basically I mad three different ways to make the same fx and I called the object in the scene with the same name: 1 Cube ScrollShader 2 Cube AmplifyVFXGraph ( I added Amplify Shader on the project ...