This has been requested before here and denied as there were some upcoming changes that haven’t happened yet:
https://forum.inaturalist.org/t/add-map-legend-for-all-overlays-on-taxon-pages/7584
Take a look at the map for Malacothamnus fremontii as an example:
https://www.inaturalist.org/taxa/70397-Malacothamnus-fremontii
This species is taxonomically messy and will require some cleanup at some point as many plants have been misidentified as or lumped in M. fremontii in the past. An important question to ask though is what the heck the pink, green, and orange on this map is showing. If you go to the legend to see, you would find this:
So now we know that the green polygons are plants, the pink ones are fungi, and the orange ones are possibly Mollusks, Arachnids, or Insects.
This is obviously very wrong and very confusing. Anything on a map should be included in the legend so you know how to interpret it. It would make most sense if the legend was dynamic and only showed what was on the map, but just adding all the possibilities is the easiest and obvious first step to avoid confusion.