Additionally, the specs appears to call out this use case:
https://ircv3.net/specs/extensions/echo-message.html
https://ircv3.net/specs/extensions/labeled-response


"There are also additional complications for self-targeted private messages."

"When a client sends a message to itself, the server MUST NOT include the label tag, except for any acknowledgment sent with the echo-message mechanism. This allows clients to differentiate between the echoed message response, and the delivered message."