I can't reproduce this.I've tried running piuparts on the .changes file, I've manually installed it into a minimal chroot, and in fact I use it in production. I used piuparts on bullseye, amd64.
Attached is the output of my run "piuparts --apt --logfile=/tmp/nagios4-cgi_4.46-2.log nagios4-cgi". It passed, of course.
If you can give me a clue on how to reproduce it, I'd appreciate it. I can't find a way to reproduce it in a few days, I'll reduce the severity.
nagios4-cgi_4.46-2.log.gz
Description: application/gzip