I found that light linking function does not really isolate a certain light from all other objects. For example, I link a cube and a point light source, and then add a plane between them, so a shadow is generated, and the light source cannot be correctly illuminated on the cube:
This problem can be solved by removing the shadow of the light source or making the plane invisible to shadow rays.
However, when I changed the plane to completely transparent and adjusted the metallicity of the cube to 1 and the roughness to 0, I should have seen a clearly highlight on the cube, just like this:
But the result was that the plane blocked the highlights generated by the light source:
and I had to link the plane to the light source to see the highlights.
Or I can choose to make the plane invisible to gloss rays.
However, the actual situation is that this plane is usually semi-transparent, and I need its correct light reflection. The above two solution will both affect my rendering results. How to solve the problem in this situation? I tried many options but no answer.