@Tralla Welcome to the forum!
I’m as stumped as you. You could hold up to ten 500-MB attachments (or a larger number of smaller files), but this is of limited use with no option to view the file contents within the app.
The only idea I had is that if I already back up my vault on a monthly basis (storing those backups outside the vault, natch), then I could perhaps start creating daily vault exports and store those as vault attachments. These daily exports would not be for disaster recovery (e.g., in case of vault corruption or lost vault access), but as a crude version-control system (to allow you to “undo” user errors like accidental edits or deletions, or as a way to get a history for fields other than the Password field). Putting the daily exports in the vault (and deleting them from your local device) will reduce clutter and wasted space on your device, and avoid expanding your vault’s attack surface.
It’s a stretch, I know, but it’s all I’ve got…
