Bezier curves can generate degenerate geometry when flattened and stroke geometry has to handle edge cases. See for instance the illustration on the last page o

Bezier curves can generate degenerate geometry when flattened and stroke geometry has to handle edge cases. See for instance the illustration on the last page of the Polar Stroking paper: https://arxiv.org/pdf/2007.00308 https://arxiv.org/pdf/2007.00308 There are also things like interpretting (conflating) coverage as alpha for analytical antialiasing methods, which lead to visible hairline cracks.