not sure if i have duplicated faces or smth like that? Thank you
HI,
That is probably because you are using Blender 4.1.
In the Course, Auto Smooth is enabled, but that doesn't exist in 4.1 anymore. You can use Object > Shade Smooth by Angle and adjust the Angle in the Adjust Last Operation Panel, or even better, use the new Modifier > Normals > Smooth by Angle.