Local Data of iOS-App is growing

The amount of local data (Settings - Common - iPhone-Storage) is steadily growing. What‘s the reason for that and how can I delete it?

It should only be temporary files that probably weren’t cleaned up (yet) because the cleanup mechanisms are more defensive (but there also cleanup mechanisms by iOS in place that would come into effect when the device is almost out of space).

When terminating the app and restarting it, all temporary files should be deleted. Does that help?

No, wether restarting the app nor restarting the iPhone didn’t help. If I understand the Cryptomator-mechanism right, the original file is sent from an app to Cryptomator, then encrypted and uploaded by Cryptomator. Seems as if there is no cleanup of cache or temporary files. Maybe it would be helpful having a „delete local data“-Button in Preferences?

After some time of testing I think that the „Excel for iPhone“-App is the reason for the growing data of the Cryptomator-App. When I use the build-in copy-function of Excel, data grows. Using the iPhone files-App to send the same Excel-file there is no growing. So the last way will be the better one. Now only the question is remaining, how to delete the local files.