If I check the storage via Settings/General/Storage & ICloud usage/Manage storage, I can see "Pythonista 458,8MB" and its "Documents & Data 65,5MB".
But I have 1,6GB of data in a user folder of Documents...
How is that possible?
I think this is because Pythonista stores its documents inside an "app group", which is a shared place where multiple apps (from the same developer) can store files. Pythonista uses this so you can access your Pythonista 2 documents from Pythonista 3. The app group doesn't belong to any single app, so it's not counted under the app size for Pythonista. I don't know if app groups are listed anywhere in the space usage list.
Thanks for you explanation.
It's strange that Apple does not foresee that in their "manage storage", isn't?