We're also facing the same issue across multiple production apps, and the error appears consistent on iOS: The operation couldn’t be completed. (com.apple.devicecheck.error error 4.) (serverUnavailable)

Yes, we are experiencing the exact same issue since Sunday, 15th June at 04:30 (UTC+7), and it has turned into a major nightmare for us. It has severely impacted a large number of users across multiple countries. This is the second time we’ve faced such an outage, and it’s extremely concerning given the scale of disruption. We had to explore temporary alternatives to mitigate the situation, but a long-term fix is absolutely necessary. Yes, I saw that. As of now, Apple’s system status page acknowledges ongoing performance issues with App Attest, but it has been over 17 hours and the problem still persists. We strongly urge Apple to investigate and resolve this urgently.