That doesn’t look like artifacts, but the Distance Field Shadow resolution being low. Use the Vizualisation View Mode for Distance Field Shadows to see what the light is computing the shadow off, and increase the resolution for either the mesh, or the global field (be wary of performance impacts when increasing the global resolution).
I suspect that you’ll see the same result if you’re not rendering in stereo. But if there is a difference between left/right eye, do let me know. Thanks!