Lumen Global Illumination foliage noise

Hi there
My foliage doing strange “waving” noises when getting mostly sky light and not direct lights

It is “fixable” with r.Lumen.ScreenProbeGather.DownsampleFactor 8 or setting “Final Gather Quality” to like 10
Both solutions are pretty bad for GPU afaik

Please let me know if you know something about it. Its ruins all of my overcast forest levels