i think this is because not every identification record is categorized as improving, leading, etc. some of the identifications show up with category=null. for example: https://api.inaturalist.org/v1/identifications?id=84340111 (https://www.inaturalist.org/identifications/84340111).
i suspect category=null is a bug(?) / data issue in at least some of these situations. for example, here’s another identification that’s almost the same as the one above, but it’s categorized as supporting (as i would expect): https://api.inaturalist.org/v1/identifications?id=84340067 (https://www.inaturalist.org/identifications/84340067).
it looks like identification records with category=null tend to show up in clustered in time. so maybe there was something going on with the system at those times. for example, in your case, you have a lot of category=null identifications from 2020-01-17 21:26:22 (-06:00) to 2020-02-05 23:02:14 (-06:00), although not every identification during that period was uncategorized.