Reproduces in both the Shadergraph and handwritten versions of the HDRP Lit shader.
Repro steps:
1. Create a material, set the shader to HDRP/Lit
2. Set the Material Type to "Specular Color"
3. Set the base map color to black
4. Set the specular color to black
5. Set the smoothness to 0.8
6. Put the material on a sphere in the scene
7. Move the camera around the sphere

Expected result: the specular highlight is completely black (not visible)
Actual result: the specular reflected light is bright white when the light is reflected at an angle (see attached image)