I assume they typoed reflinking, a way of doing CoW-based copying of file contents.
I was under the impression it could do that, I think I build a snapshotting mechanism using this.
rsync does not have the ability to copy a file using the filesystem's copy-on-write feature. This is unlike cp, which has the --reflink flag. Here's the bug report on GitHub which the developers closed as "won't fix for now":