You should never store unencrypted secrets, like this export file, on an unencrypted disk. Not even temporarily.
Instead, create a small encrypted drive on a pendrive or as a file with LUKS or Veracrypt, mount it, and save the file _directly_ there.
If your self hosting bw then there is a better way. The vault is encrypted at rest. Just back that up via borgbackup. No questionable plain text step. No reminders, just nightly incremental backup