As of 12/1/2022 Geocodio now returns county-equivalent designations based on Connecticut's 9 Councils of Government for the "county" value in API responses and for processed spreadsheets.
Almost all functions of county government were abolished in Connecticut in 1960. Due to this, Connecticut has decided to officially migrate from using legacy County designations to county-equivalents based on Connecticut's 9 Councils of Government for statistical purposes.
You can read more about this change here: https://www2.census.gov/geo/pdfs/reference/ct_county_equiv_change.pdf