[Python] Incorrect leftover point when subtracting overlap between two polygons

I am identifying polygons that intersect, then computing their intersection and removing it from the first polygon. I get a weird left-over point. If I just take the difference between the polygons this doesn't happen. Why?

import pandas as pd
import geopandas as gpd
import shapely

test = pd.DataFrame({"geo_uuid": ["a", "b"], "geometry": [shapely.from_wkt("POLYGON ((-85.489530540446 40.72197039620563, -85.54038813980434 40.686016211216575, -85.42963027177998 40.682309666676865, -85.489530540446 40.72197039620563))"),
shapely.from_wkt("POLYGON ((-85.52717584228726 40.732495186799525, -85.49542480146151 40.693215026642285, -85.44637022730953 40.73203119983377, -85.52717584228726 40.732495186799525))")]})

test = gpd.GeoDataFrame(test).set_geometry("geometry").set_crs(epsg=4326)

geo_1 = test.geometry.values[0]
geo_2 = test.geometry.values[1]

overlap = geo_1.intersection(geo_2)
geo_1_overlap_removed = geo_1.difference(overlap) # this will have an extra point contained in geo_2

geo_1_minus_geo_2 = geo_1.difference(geo_2) # this is good



Why does this happen? What am I doing wrong?

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