From how I read it is not a Debian bug. They marked cloud-init as conflicting with firewalld, as it can cause a systemd loop problem. Debian bug report:
Where a firewalld can get killed at startup to proceed. I ran into it on Debian 11:
Here’s the firewalld bug report: systemd unit file: possible dependency loop · Issue #414 · firewalld/firewalld · GitHub
And the cloud-init: Bug #1956629 “cloud-init.service/start deleted to break ordering...” : Bugs : cloud-init package : Ubuntu
On Hetzner, where I am, I can just remove cloud-init as it is only used at first boot to install SSH keys, etc. From what I read AWS needs cloud-init installed and the best option is to use the Security Groups external firewall.