Three problems with strokes. Here is a sample file. sample.afdesign Stroke to a curve with pressure. 1. Stroke is rendered with some kind of jitter. This happens very often to strokes with pressure. 2. If you apply Layer > Expand Stroke, round edges get sharp points. This happens even without pressure. 3. Again, Layer > Expand Stroke is very inaccurate. Blue: Original Red: Expanded stroke While an offset of a bezier curve cannot always be exactly converted to another bezier curve, Affinity Designer's accuracy is very poor compared to Adobe Illustrator's.