I get strange artefacts from the smoke domain where density should be zero but the domain box is over other collision objects in cycles (Blender 2.92 and 2.93 beta). Res seems high enough. For some reason, it seems to be caused by reflected rays of textured surfaces that are inside the smoke domain box.
I'm not sure what causes this to happen but I am trying to find a way around this. If I disable the material input node, it goes away. If I render with no smoke the objects are ok. So the domain seems to affect the non-smoke area. Any ideas?