I’ve just created a superbasic glossy shader but I cannot imagine why there are that black artifacts on the reflection, notice that they ray amount has been set to 32 so it shouldn’t be the problem.
Hi. You share .blend file.
Or at least you share an screenshot of the mesh in Edit mode, and your configuration in Sampling and Light Paths in Render tab. Also, Subdivision modifier settings if you are using it.
Is it possible to convert triangles to quads in your mesh, and apply subsurf modifier with great subdivision level?
You read in the link that lsscpp has given and search in google about Terminator problem that is common in engines like Cycles when there is not enough geometry.
Converting tris to quads and applying subsurf helps a lot at the edges.
Increasing “Glossy” bounces in Light Paths item helps in other dark areas, but increases noise (Maybe Clam indirect is necessary)