All deployments from around 15:40 UTC might be shown in a FAILED state, even though they were successful. It's just a matter of display and the instances, if correctly deployed, are put into production.
The Activity pane (Console), clever status (cli) and the API endpoint /applications/<app>/deployments incorrectly report the deployment status.
Notifications (slack webhooks, mails) correctly report the deployment status (failed or successful) and can be trusted.
EDIT 21:48 UTC: It should now be fixed. Deployments with the "FAILED" state will keep their broken state.