Those are called poly lines and its how curves are defined in DWG and DXF- the traditional workaround was to increase the poly line resolution in the app you are importing from and the app you are exporting from, so that the straight line segments would be so short as to be effectively a curve as far as any CNC or waterjet system knows.
( e.g. slicer software for 3D printers still represents curves as a series of very short straight line segments and the length limit for these segments can be user defined )
Supposedly, there is a 3D DWG/DXF format that CAN export parametric arcs in the file format without conversion to polylines… but I do not know if Shapr exports in this file format.
Whatever software you are importing to- check and see if there is an option for 3D DXF and if it imports curves, then Shapr is exporting a 3D DXF.
Alternatively, I do not know if Shapr will export sketches in IGES or only actual models. But you could try IGES export and see if that brings in the splines. IGES is capable of saving spline and parametric lines…
As I see the software you are using (AutoCAD I guess) can measure the radius of the holes which would not be possible if the circle is made of polylines - similar issue like you try to measure the radius of a hole of a mesh model.
Is it possible that it is a result of your display settings?