defaultConvexity

When a polyhedron or an extrusion do not have an explicit convexity, then this value is used.

Because FooCAD has a convexity on Shape2d, extrusions of circles and squares will have the efficient (and correct) convexity of 1.

If you want the old behavior (of using leaving convexity unset, and letting OpenSCAD use its default of 1), then set this to null.