Poor wording on my part.
Before I got a UPS, I had my power cut out or surge from time to time. On two separate occasions files were being written when my computer shut off, and got stuck in a strange not-a-file not-a-dir state. The files and their parent folders could not be deleted, but I could format the partition to clear them. One happened to be in my temp folder, which is how I first discovered the issue.
As long as power is restored shortly, SSDs are supposed to complete the write... or is that only server grade ones? Either way, SRAM holds data longer than DRAM, so if the controller is programmed to, there's a chance it'll work.
The most important early product on the way to developing a good product is an imperfect version.