Hi,
I am using argis package version 2.0.1 and it appears to be an issue in this version. I have been trying to troubleshoot where the change in datetimes occurs in a scripl figuring it was earlier in the script tool but I've narrowed it down to later when I use the spatial.to_featureset()
I also found the link below on github.
I have to admit its pretty discouraging since I've been working to update code from arcpy to the API only to run into this bug.
df = s_lyr.query(where = AK_dt_fltr, out_sr = 26931).sdf
gsa = GeoSeriesAccessor(df['SHAPE'])
df['LENGTH_NM'] = gsa.get_length('PLANAR', 'NAUTICALMILES')
s_lyr.edit_features(updates = df.spatial.to_featureset())
https://github.com/Esri/arcgis-python-api/issues/1301