Just yesterday I happened to be looking around for a way to have iNaturalist tell you which of your observations was least observed on the website overall. I found some people asking about that, but no very good solution. So in truth, I don’t really know! In my case, I doubt it would have been a very rare species.
I looked around a bit randomly using the compare tool suggested in that thread I linked, and it looks like this one only had 107 observations, but that’s still not exceedingly rare, I suppose…