I know there are many vines with variegated foliage .... a 1/3 of the Ipomoea Nil cultivars have variegated foliage.
But here I speak about purpurea!
I collect the seeds and I get only regular ipomoea purpurea.
Every year there are 5/6 plants ... volunteers who have variegated foliage. You never know where they will appear. Ipomoea purpurea with variegated green / white cream leaves in are rare.
Here another:
Other purpurea have variegated foliage that spreads by seed: