You probably need to post more information - perhaps a node setup. My first reaction to seeing the image above was “cool material, looks a bit like carbon fibre”
Is it not supposed to look like that?
I guess one thing to check is that you haven’t inadvertently duplicated the geometry and therefore have coincident/overlapping faces - that can cause artifacts of the type seen here.
If duplicated geometry isn’t the problem…check your clipping distance. This looks like a very small mesh…and clipping can add strange artifacts as well as vanishing mesh when too close or far away…