/e/ Cloud data use

I have my own Nextcloud and don’t actually use the E.Cloud.
Yesterday, my “/e/ storage” Cloud APP suddenly consumed 800Mb of data volume without saving anything.
Yesterday I went for a bike ride near the border.

Question: Does anyone know why the /E/ app suddenly ate up so much memory without any data being transferred to the E Cloud?
Can I easily switch off all data use in the /E/ app?