I'm trying to achive something really simple but I've got the annoying effect. I'm using Cycles for rendering. On some meshes I applied the solid color wihtout any special effects (just the Diffuse BSDF with the chosen RGB color). I have one point light and a surface shader set in World Properties. The area on which the strange effect appears doesn't have multiple faces, in which case some problems with normals might appear. I even didn't know how to name this visible effect, so it was difficult to find the solution somewhere. It's something like a shades along the faces. If there is already an answer on this forum, sorry I didn't find it - please direct me to this answer.
Thank you in advance for any help. Probably it is something very simple. But I don't have much experience in Blender, especially in materials and rendering.
Mariusz