So to do this, I used bezier curve, that I extruded and then converted into meshes… Then I used a boolean modifier, but didn’t really get the effect I wanted (here’s a photo with the bezier meshes hidden) :
Could be many things…I would start trying these options:
It looks like you also have a bevel modifier. If so check the harden normals option in the bevel modifier
recalculate the normals. alt + n —> recalculate outside
turn on auto smooth. Its in the properties panel to the right. --> click Object Data Properties, the icon looking like a triangle --> select normals and check the auto smooth.
