This incident has been resolved. Affected unsubscribe events have been replayed. And as noted before, inbound subscriptions during the incident period can not be replayed.
As of 6:07pm (US Eastern) all messages that were delayed or failed to send properly during this window have been sent. Marking this incident as Resolved.
Beginning at 1:46 PM US Eastern Time and ending at 5:11 PM US Eastern Time, Klaviyo began experiencing issues with the submission of Klaviyo reviews. Any end user review submissions during this time would have been unsuccessful.
The root cause has been identified and addressed, all Reviews functionality has been restored.