Google Maps API version 3.48 changed the default map style.
Is it possible to revert the old map style using map config or API config?
Perhaps you could use Google's documentation at https://developers.google.com/maps/documentation/cloud-customization/overview to create a custom style that mimics the old map style. You go to https://console.cloud.google.com/home/dashboard to your project, then you can go to Other Google Products -> Google Maps -> Map style.