Thanks for the information, in your scene you’re using NONE as your anti-alias?
If I use TAA the problem is fixed but I cant render 4K in TAA
I increased Spatial samples and there isn’t too much difference, i checked what you said about the type of shadow, and in Hard shadow I’m getting a black glass in my scene, but if i deactivate the shadows there is less noise. Give me the impression that even when i increase the whole scene the sampling, inside the refraction the scene has a sampling of 1.
Sadly in my scene I have a ton of decals for details and Pathtracer doesn’t render them
EDIT:
I turn off a lot of elements in my scene to find what is messing my scene. I foudn that one of my elements that uses emission is making a ton of noise in the glass
for now i unchecked the Cast Shadow on that element and my glass is looking clean, i will keep reactivating my elements