Lighting & Shadow Subsurface Artifacts - What is the cause and how to remove them?

Hi. I am using Unreal Engine 5.6.1 on Mac OS, M3 Pro Max 128GB RAM. Beginning to use Unreal Engine for some real-time look development, as opposed to Marmoset Toolbag. I’ve setup an empty scene, with a test portrait (smoothed mesh normals), and Alembic Groom, following the Epic Games Documentation SSS Profile Guide, and Epic Games Documentation Groom Simulation and Rendering Quick Start Guide. Everything in my scene is default, with three Moveable Rectangle Lights. In the viewport, I see artifacts, which appear to look like noise in the shadows.

Attached is a screenshot for your viewing. What could be the potential cause of this, and are there any specific settings/workarounds that I can look into, to resolve this issue? I have not learned the rendering process within Unreal Engine just yet, so I am using the High Resolution Screenshot function within the viewport.

Thank you for any insight into this matter!

Bumping for visibility. Thank you.