The DKIM-Signature has expired on the message and will result in a DKIM FAILURE result at all inboxes.
This expiration tag ("x" tag) is found in the DKIM-Signature headers of outbound messages. This tag contains a specified timestamp for the date when this DKIM key should be treated as revoked by mail servers.
Some senders actively use expiration tags as a way to manage/cycle through new DKIM keys as an additional way to lessen the risk of malicious actors from possibly gaining access to a DKIM key to fool message recipients into opening malicious messages.