discrepancies between species count on the profile vs explore page have been reported occasionally before (ex. https://forum.inaturalist.org/t/different-number-of-species-in-profile-vs-explore/40617), and i assume they are related to occasional reports of discrepancies between observation count on profile vs explore page (ex. https://forum.inaturalist.org/t/discrepancy-in-observation-count-between-profile-page-and-explore-page/20009, https://forum.inaturalist.org/t/zero-observations-for-user-with-one-observation/4407). in these cases, it seems like the problem will resolve itself, seemingly spontaneously.
i would guess that whatever mechanism updates the profile just occasionally does not get triggered or fails to run completely. so i don’t know that anyone has ever tried before, but i would try just adding a dummy casual observation of a random species that you’ve never observed before, and see if that triggers that mechanism to update your species count appropriately. if so, then delete the dummy observation, and all is fine in the world.