The firewalld package prior to version 0.8.1-2 was missing the compiled python modules. This has been fixed in 0.8.1-2, so the upgrade will need to overwrite the untracked pyc files created. If you get errors like these
firewalld: /usr/lib/python3.8/site-packages/firewall/__pycache__/__init__.cpython-38.pyc exists in filesystem firewalld: /usr/lib/python3.8/site-packages/firewall/__pycache__/client.cpython-38.pyc exists in filesystem firewalld: /usr/lib/python3.8/site-packages/firewall/__pycache__/dbus_utils.cpython-38.pyc exists in filesystem ...many more...
when updating, use
pacman -Suy --overwrite /usr/lib/python3.8/site-packages/firewall/*
to perform the upgrade.