DJI recently made a change with Go 4.02 on Android and moved map provider from the default Google Maps to Here Maps.
A workaround that allows you to get Google Maps back been found and is as follows.
First of all your Android device needs to be rooted to be able to do this, if you don’t know how to do this on your specific device try looking on XDA Developers Forum for detailed info.
Once your rooted you need to make sure DJI Go 4 is completely closed in the background then download and install an app called Disable Services from the Play Store
When you open it you will get init map error, this can just be ignored.
As for the reason why DJI moved over to Here Maps it’s currently unknown but this workaround allows users who do fly in the areas Here was poor to get back to where they were before with out using an older version of DJI Go.