Was it always a big mystery? Or did we think we understood it the whole time, but only just recently discovered that we actually didn't?
What the researchers are reporting appears to be a more detailed structural description of this sensory protein complex, and the additional structure information combined with simulations of known physics and chemistry in turn suggests additional detail about of how the "signal" occurs on the molecular level.
Disclaimer that I didn't take time to read the whole thing now, but that's the gist of it from summaries and skimming.
It is, with little doubt, some valuable pieces of information in the context Collective Knowledge of Mankind, and keeping large, complex, multipart molecular machines like this reasonably stable and normal for examination is arduous work, so I don't mean to denigrate the studies or the scientific paper, but as so often the way this is being spun in the press release is regrettable.