I tried different light settings and found that contact shadows, when they were on at all, produced some odd artifacting on my pins. Here is a comparison:
Low res shadows (512px):
High res shadows (1024px):
High res with contact shadows (notice the artifacts on the pin body):
Eevee settings? Interesting I will have to try to remember contact shadows causes that artefact I have seen it elsewhere. Eevee is great for speed but makes it complicated turning on things that get it closer to Cycles.
those artefacts I have only have seen on Cycles renders. Which is a known problem in Cycles. Cause by too low poly (too low vertices/faces).
The contact/ambient shadows do have an option for how strong this needs to be, maybe too strong in your case. Definitely check some shadow options.
Check also the subsurface modifier! (or add it to the pins).
But check also the face normals. In edit mode, select all vertices and press shift n.
To push normal to the out side.
