What does "INFO reaped unknown pid" in the log mean?

With cron running under supervisor at loglevel 'info' and a job that runs every 60 seconds, the supervisor log receives a new message every minute:

2022-09-23 19:40:05,839 INFO reaped unknown pid 10547 (exit status 0)

Searching the documentation for "reap" yields only one result (the changelog) with no clear explanation of why I should care that supervisor reaped an unknown pid with exit status 0.

Expectation: if there is some change I should make to my deployment, I should be able to find that in the documentation. If it means nothing to me, it should be a debug message so that I can isolate it from the interesting INFO events about service startup.