I was confused about what the high and low rank options in the filters window actually meant until just now. The reason is that (at least on Mac with Safari) the heading for ‘high’ and ‘low’ appear in the list as the first option.
It would be much easier to understand if ‘low’ and ‘high’ were headings above the drop down.
I also agree, I’m not even sure why infraspecifics don’t show up in the ‘species’ panel when searching for flora.
That’s a different topic than search filters; you can read more about how iNaturalist counts taxa here:
https://www.inaturalist.org/pages/how_inaturalist_counts_taxa
I’m going to close this topic as it’s not a change we’ll be making.