tasks/set_facts_.yaml has what is now incorrect use of {{ }} syntax, prevents successful run

In this file ocp4-helpernode/tasks/set_facts_.yaml on line 20 is this
critical_services: "{{ critical_services }} + [ 'dhcpd' ]"
but should instead be this
critical_services: "{{ critical_services + [ 'dhcpd' ] }}"

and line 25 is this
critical_services: "{{ critical_services }} + [ 'keepalived' ]"
but should instead be this
critical_services: "{{ critical_services + [ 'keepalived' ] }}"

I had to make these changes based on advice from peer to get this playbook to run on an IBM Power8 environment in IBM Tech Zone.
In case it's considered relevant, my bastion host (i.e. helper node) is running RHEL 8.4, ansible version info as follows:
ansible [core 2.13.3]
config file = /etc/ansible/ansible.cfg
configured module search path = ['/home/cecuser/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
ansible python module location = /usr/lib/python3.9/site-packages/ansible
ansible collection location = /home/cecuser/.ansible/collections:/usr/share/ansible/collections
executable location = /usr/bin/ansible
python version = 3.9.13 (main, Nov 9 2022, 13:29:05) [GCC 8.5.0 20210514 (Red Hat 8.5.0-15)]
jinja version = 3.1.2
libyaml = True

Open ocp4-helpernode/tasks/set_facts_.yaml and inspect lines 20 and 25, where critical_services is extended with dhcpd and keepalived. Run the playbook with Ansible 2.13.3 and confirm it completes successfully on the reported environment without the template syntax error.