Your images present a really accurate picture of what's happening; thanks for posting them. I have a couple of questions so I can better report this to the product team:
What device are you on and what version of the operating system is on it?
What version of Fresco are you using?
If it's easier for you, you can message me through Fresco's Report A Bug link and all of your device/app information will automatically populate the email. (Tap the gear icon in the upper nav of the Home screen, then App Settings > Help > Support > Report A Bug.)
We do see this as well when filling circles. The team is logging a bug so it can take a closer look at what's going on. Based on your images, I think I have your steps but wanted to make sure that I'm not missing any:
1. Place a shape on the canvas.
2. Tap Fill and choose Vector.
3. When zooming in (at 600%) you see a wavy/choppy shape border.