iPhone NSPOSIXErrorDomain Code=80 "Authentication error"?

Recently my iPhone (13 Pro, iOS 17.51.(21F90)) started to crash all non-Apple apps on launch. I've tried four rounds of Apple phone support. I've executed the usual list of steps (update, reboot, reinstall, etc.) each time. During these sessions the problem goes away, but always returns later and the same action do not resolve it. Based on hints from other postings, I hooked up a console for the iPhone on a Mac. I don't understand the messages I see, but I find the following whenever an app crashed on launch:

error com.apple.runningboard Launch failed with Error Domain=NSPOSIXErrorDomain Code=80 "Authentication error" UserInfo={NSLocalizedDescription=Launchd job spawn failed} runningboardd

My attempts to convey this to Apple support have failed. One support person had never heard of the console app; another suggested that I was hacking my iPhone and was therefore not supported.

Has anyone seen this error? Where can I find out its meaning, case, and resolution? Any tips?