Why is there an 'external' label on my transaction?

Vault spends conducted outside of the Unchained platform are labeled as such

As an Unchained client, sovereign vault recovery is always available to you through open-source applications. There are many, but our recommended method is the multisig wallet coordinator that we built specifically for this purpose: Caravan. You can learn how to use your keys and wallet configuration file to recover your vault in our article on the topic.

What does the external label mean?

When you use one of these open-source applications to conduct a spend from your vault, the Unchained platform recognizes the spend and applies an External label to the transaction.

The label highlights that there was something unique about the transaction—in this case, that it was authored, signed, and broadcast using something other than the Unchained platform.