Service Account API keys Disappearing

The audit logs would be the first place to check. In the other topic I linked above, the OP mentioned they could not find any audit log entries related to the missing key.

Today, OpenAI published an update on the status page stating that the audit logs were affected by a bug and that the missing data is currently being backfilled.

That may help clarify what happened.

OpenAI Status

Issues with API Platform Audit Logs - OpenAI Status

We have observed issues with API Platform audit logs.