As discussed, this issue could be in the dnf package which didn't have the PLUGINPATH updated to Debian's path, which could be verified in /usr/lib/python3/dist-packages/dnf/const.py.
Can be worked around by adding the following line in [main] section of /etc/dnf/dnf.conf: pluginpath=/usr/lib/python3/dist-packages/dnf-plugins Regards, Aron