Just recently experienced this. Interviewed at a FAANG company, process started 5 months ago, about 50 emails exchanged, a dozen or so phone calls of various kinds. 6 interviews, they came back and asked to re-do 1 of them, which I obliged. Then, they were silent for about 2 weeks, I asked about the status and they said they want to re-do 2 more interviews. I kindly refused and they said they wouldn't move forward.