I’m not entirely sure this is the place to post this, since I’m not seeing any prior mention of &unobserved_by_user_id=
However, when I use it, I do get species showing up that I have observed, for example here:
https://www.inaturalist.org/observations?place_id=118376&subview=grid&unobserved_by_user_id=gwark&view=species
I (gwark) have multiple observations of Trichoderma - is this showing up because it’s only excluding species that have been observed by me?