Why does my spot light + volume fog always have something like a Mosaic

[41LAB]

Why does my spot light + volume fog always have something like a Mosaic and motion blur when changing position

[anon84199231]

You should try this command “r.VolumetricFog.GridPixelSize” and “r.VolumetricFog.HistoryMissSupersampleCount”.
GridPixelSize is xy pixel size per cell.(I recommend set to 2)
HistoryMissSupersampleCount is decrease noise when camera pan and camera cut,but increase cost.