PluginKit Code 4 error and fail to launch notification service extension

I've got an app which has a notification service extension (and has had so for a few years). I noticed that the pushes were getting delivered directly to the user for a handset, and in the log could see a SpringBoard error saying

Error Domain=PluginKit Code=4 RBSLanchRequest error trying to launch plugin Error Domain=RBSRequestErrorDomain Code=5 Launch failed ErrorDomain=NSPOSIXErrorDomain Code=111 Unknown error:111

I rebooted the phone and it started working as expected. But it's worrisome this happened, and it's not the first time I've seen it either.

Observed with iOS 17.3.1