bitcoin/doc/release-notes-30239.md

P2P and network changes

Ephemeral dust is a new concept that allows a single dust output in a transaction, provided the transaction is zero fee. In order to spend any unconfirmed outputs from this transaction, the spender must also spend this dust in addition to any other outputs.

In other words, this type of transaction should be created in a transaction package where the dust is both created and spent simultaneously.