If using a predefined SSH key pair on Debian 10, the comment of the public key will be removed (probably by the community.crypto.openssh_keypair module) when added to the flatcar-linux-config.yml.j2 template.
See failed CI job: https://gitlab.com/hifis/ansible/gitlab-ci-openstack/-/jobs/1436902366#L1153
(Workaround: Removed the comment from test public key: https://gitlab.com/hifis/ansible/gitlab-ci-openstack/-/merge_requests/28/diffs?commit_id=dbf941e30cffe7781da2bc094e71e63d2b48a5aa)
Recreated from https://gitlab.com/hifis/ansible/gitlab-ci-openstack/-/issues/26