Taking already shared credentials from an organization and placing them into a private vault essentially implies them to have been compromised—as far as private utility is concerned—even if it’s sometimes only a theoretical risk. This is the “data can’t be truly unshared” issue.
To help solve that, after “unsharing”, these credentials could be visually “attention needed” flagged as being compromised, as a reminder and means of tracking whether they’ve yet been changed.
Each unshared item could have a single flag, or Bitwarden could specifically and granularly track the last change date of their secrets (passwords, TOTP keys and hidden fields). Unflagging can also either be manual, or automatic after changing the relevant values.
(I posted a much more extensive, organization-vault version of such flagging in another feature request, but you don’t have to go there for details relevant to personal-vault unshare flagging.)