That gets one suspect out of the way. A quick glance at Jottacloud also looked clean (unlike others). Actually studying the damage could be done with a look in the database plus a close view of the file.
Database has expected length and hash in RemoteVolumeTable. Hash work is a bit more indirect…
–upload-verification-file can avoid viewing the DB, e.g. in DB Browser for SQLite, if that’s any easier.