I do not see the error in the PG ;(
Can you see my image? When I change the visibility property of the ground to 0.6, the particle system becomes blurry.
The first image shows a clear boundary line where the background above it is the sky and the particle system is clear. However, below it is the ground with its visibility property changed, causing blurriness. I’ve tried testing with various visibility values and found that when the visibility value is between 0.5 and 1, it appears the most blurry
You can fix that problem by forcing the particles to render after the transparent object:
Babylon.js Playground (babylonjs.com)
set.systems.forEach(s => s.renderingGroupId = 1)
But if you want to do that you have to prevent the camera to go below the ground or it will be weird.
The reason is that by default, Babylon renders transparent objects after particles