The purple lines taken away: the orange lines are just where they were, and the ring looks as white as the middle.
Tricks of color
Watercolor illusion
Is the ring between the two wiggly outlines faintly orange?
No: it is the same pure white as the middle and the outside. Only the thin orange lines along its edges are colored.
Why? Your brain spreads the color of a thin edge into the white on its side, as if you had painted it with watercolor, until the next line stops it. The orange lines face the ring, so only the ring is tinted.
Picture: Drawn by Science Playground, after Baingio Pinna · Wikipedia(opens in a new tab)