I notice a new icon on the right side menu. It’s a sphere with a grid on the right hemisphere. There you can toggle on or off either Soften Coplanar Edges or Smooth Edges (or both). It is not part of the Eyeglass icon any more. There is also an Angle index, and it shows 30 in the screenshot. What does that mean?
On Pro it’s also a separate panel.
Soften will make the lines disappear but the ridges remain.
smooth will make both gone, like on a cylindre.
the angle is the angle between the normals :
when you have two faces meeting, it’s complex to calculate the exact angle between them.
BUT it’s easier to draw their normals (a simple line perpendicular to each face, easy), and calculate the angle between them.
THIS is this angle.
when you push the angle to 0°, then NONE of the selected faces and lines are softened. when you push on - say - 16°, it will consider all the faces with a perpendicular angle lower than 16° as smooth. and so on.
A 24-sided cylindre has 24 faces, meaning the angle between each is 15°. take a cylindre, push the cursor below 15° you’ll see all the lines. push it above 15° and you’ll see them gone. (no need to go higher then.)
you can check pro’s help page, the interface is a bit different, but the idea is the same
The angle adjustment is basically instructions to SketchUp that helps it understand whether the angle between 2 flat faces should be treated as 2 separate flat things or if they are actually 2 faces being used to represent a curved surface.
This affects both the rendering side of SketchUp - for example whether a sphere or polyhedron should look faceted (or whether it looks like a sphere, but also when you select a face, does it treat it as 2 faces or as one contiguous surface.