As the others have said it is a long term graphic issue. It is related to z-fighting and clipping and is basically about how the camera works with faces and edges and distances within 3d.
One of the easiest fixes is, as you mentioned (not to mention), to actually hide the edges on the top of your trusses. If you have created them as components it should take a few clicks to fix them.
Here’s an example from about a decade ago showing how it works.