Thanks for the report!
I can reproduce it here on my system.
$ curl -k --silent 'https://centos8-stream-katello-4-5.tanso.example.com/pulp_ansible/galaxy/Default_Organization/Library/custom/lol/ansible/api/v3/plugin/ansible/content/Default_Organization/Library/custom/lol/ansible/collections/index/theforeman/foreman/versions/3.4.0/' | python -m json.tool | grep download_url
"download_url": "centos8-stream-katello-4-5.tanso.example.com/pulp_ansible/galaxy/default/api/v3/plugin/ansible/content/Default_Organization/Library/custom/lol/ansible/collections/artifacts/theforeman-foreman-3.4.0.tar.gz",