Lat and lng are required to place the markers on the maps, but also to determine which listings are near you. The geo-location works by checking your lat and lng and then serve listings that are near your lat and lng.
This may explain a bit more: https://wpgeodirectory.com/docs/search-filters-overview/#redirect
Check out the second option: Redirect to nearest location (on first time load users will be auto geolocated and redirected to nearest geolocation found)
1. If there are no listings with any lat and lng near you, you will be redirected to the location page near you and you will see listings that have that location as the address.
2. If there are listings with any lat and lng near you, you will be redirected to a page showing those listings with the near lat and lng.
So it seems you now have added lat and lng to att least one listing near you, and therefore the behavior has changed. You are no longer redirected based on address, but on lat and lng.
Thanks