Following the description here:

https://humankind.fandom.com/wiki/Influence#Science_Osmosis

Science Osmosis is being triggered because my city is supposedly under the sphere of influence of Unknown (Blue). However, not only is the city still in my sphere of influence, the faction in question has no influence over my city at all. The only other culture contesting the city are the Olmecs.

Edit: Large map, 10 players.