Since the owner's keys might have leaked, `Kind:18`s **alone** can't be trusted.
Close acquaintances to the owner should verify the owner's intention off nostr and signal their conclusion by adding the new key to their contact lists.
The presence of one or more `kind:18`s, no matter who writes it, declares the key to be out of use, unreliable, unsafe and potentially stolen: No event, past and future, from this key can be trusted anymore.
Clients SHOULD use Generic Repost (`kind:16`) with a stringified version of the `kind:18` and a `k` tag to `18` to let users warn followers and guarantee `kind:18`'s retention as much as possible.
Generic Re-posts events simply warn followers and MUST NOT be considered the user's final decision on which key to switch to. Contact lists are the only source of confirmation.