https://developer.apple.com/documentation/metrickit
I am unable to get the MetricKit logs for past 24 hours time period on my test flight build. I have been able to achieve immediate logs for crash, cpu exception and diskwrite exceptions. But the logs which contains all the crashes, cpu exceptions and diskwrite exceptions, battery and network details, etc for the previous day/24h are never generated. I have used the following method to log the payloads in the file systems. I have tested the same on normal xcode builds as well as TestFlight build.
func didReceive(_ payloads: [MXDiagnosticPayload])
https://developer.apple.com/documentation/metrickit/mxmetricmanagersubscriber/didreceive(_:)-9yd4u