I've implemented a PBR rendered using OpenGL in my deferred rendering engine. The problem is that there are strange signs on my object as the roughness increases.
You can see this on these images:
I've found out that the problem is with the filtering. Using LINEAR_MIPMAP_LINEAR gives the results shown above, but when I use NEAREST_MIPMAP_LINEAR the strange seams aren't present but when the surface is more rough you can see the pixels of the texture (as you can see on the image below).
As Robinson mentioned in his comment, reading the article he posted showed me the answer: i just needed to enable GL_TEXTURE_CUBE_MAP_SEAMLESS on my cubemap texture.