I think something with the material. It is the Eucalyptus White Hardboard from Home Depot.
I think maybe the coating is seperating from the material or maybe the material is lifting slightly as it is cut out and changes the focus. But I don’t think that is it, because I saw similar thing happen on a parallel line cut.
your drawing are a lots of lines with attached with nodes… polyline is one line.
you can see the differents when you select it. i like poly lines better because its always finish a line first before it starts a new line