Package: cdbs Version: 0.4.163 Severity: Serious /usr/lib/cdbs/waf-unpack is using /usr/bin/python and it's syntax is Python 2 only. I have no clue what a WAF is, so I didn't spend time trying to fix this issue, sorry.
Marking as serious as Python 2.7 is EOL and https://wiki.debian.org/Python/2Removal clearly says that packages are not allowed to rely on it. cdbs also doesn't depend on python-is-python2, which could be argued to allow this usage, so it is actually broken in Bullseye. Cheers, Sven