Illustrator will also show seams in most cases the same as Affinity. Photoshop vector tools will also act the same for different coloured objects next to each other.   Flash is the only rasteriser that doesn't show seams that I know of and that's because it uses a completely different method and causes many other terrible problems at the same time.   We can improve the seams a bit by adjusting gamma on outer edges and pixel aligning logical op results but the problem will never go away for d