Pixelated animated flag shadows

Does anyone know why I get this pixelated shadowing on an animated flag in my raytrace scene? All other assets are fine as you can see with the floor in Image. Lighting is HDRI with one directional light … Thanks for any help

That doesn’t look like shadowing, looks to me like z-fighting, like you’ve got two meshes in the same space. Is it possible that the flag has a mesh facing each direction rather than using a two-sided material?

Thanks…It’s definitely one piece of geometry. So I played around with some settings in raytracing for both the directional light and the mesh and things seems to have improved a bit. Is there a away to improve the quality of raytraced moving shadows? Samples per pixel under raytracing in the directional just seems to slow things down increasing it…I have it set to 1 right now.