Hi,

Does anybody know what data the app DGI GO is constantly transfering even while I'm not using the drone or app at all?
The app is also using a lot of battery. Before I installed it, I could use my phone for more then 1 day without charging.
Since the installation it last nearly 14 hours... and it is constantly sending some data...

Somebody any idea?

It's been reported before in several threads.  You may want to check on running processes in your phone and stop any DJI GO 4 process.  There could be several.