Hey. They changed a lot from the ea to the preview. There are ways to improve noise on foliage but that will have a huge performance impact. Basically you can improve it a lot by cranking up the final gather quality and setting the Global Illumination quality to cinematic. If I find a better solution to deal with the noise on grass I’ll post it here.
Update:
Try setting:
r.Lumen.ScreenProbeGather.TemporalFilterProbes = 1
That made difference for me.