Hm, yes, I was thinking the same.I've seen this question not long ago without a great answer
In theory, it shouldn't hurt. But considering that many people believe that the DNS backend is part of a footprint that Google saves and tracks, it may flag you somehow, but not sure how.
In practice, I would say, that since fast flux are generally shared with evil practices, you may end on some flagged IP that will severely hurt your rankings at some point