I have a NURBS surface bounded by a single spline edge.
On the attached image you can see the green triangulation deviating significantly from the red spline curve.
The triangulation is done using an absolute deflection value of 20.0 and an angular deflection of 0.1*PI
The smaller the angular deflection, the worse the error.
In the next message, a BRepTools::Write dump of the face causing the error is attached.