When creating a role or a collection and sharing it on Ansible-Galaxy, the latter links the role/collection to Github code repositories of its author. By default, it points to master but our master branch in GitHub repo has been renamed as main so it's impossible for ansible to pull sources. github_branch option in meta/main.yml needs to be added. For more info see here
Even after merge request, issue is still there. Ansible-galaxy is unable to pull main branch, uses master instead.
Issue is discussed there: https://github.com/ansible/galaxy/issues/2535