If you check the NIP-4 GitHub page now, you will see "deprecated in favor of NIP-17."

So, let's analyze the kind-17 using the following thought framework.

Kind-17 separates the sending address from the ID, making the sending address random and hiding the sender's real ID, thereby improving metadata privacy.

https://github.com/nostr-protocol/nips/blob/master/04.md

https://github.com/nostr-protocol/nips/blob/master/17.md nostr:note1zkkxvfetp5entw9aq3s3jn2e0s5p3kurz0zudprz8ygtaagek64shahcv2