Ansible BUG: include_tasks with loop and when condition

playbook.yml

- hosts: localhost
  gather_facts: false
  vars:
    # default_state: absent
    tasks:
      - name: task1
      - name: task2

  tasks:
    - debug:
        var: task.state | default(default_state)
      loop: "{{ tasks }}"
      loop_control:
        label: item.name
        loop_var: task

    - include_tasks: tasks.yml
      loop: "{{ tasks }}"
      loop_control:
        label: item.name
        loop_var: task
      when: task.state | default(default_state) == 'present'

Output. Tasks are running but shouldn't: null == 'present'?

PLAY [localhost] **********************************************************************************************************************************************

TASK [debug] **************************************************************************************************************************************************
ok: [localhost] => (item=item.name) => {
    "task": {
        "name": "task1"
    },
    "task.state | default(default_state)": "VARIABLE IS NOT DEFINED!"
}
ok: [localhost] => (item=item.name) => {
    "task": {
        "name": "task2"
    },
    "task.state | default(default_state)": "VARIABLE IS NOT DEFINED!"
}

TASK [include_tasks] ******************************************************************************************************************************************
included: playbooks/tasks.yml for localhost
included: playbooks/tasks.yml for localhost

TASK [debug] **************************************************************************************************************************************************
ok: [localhost] => {
    "msg": "Task is running"
}

TASK [debug] **************************************************************************************************************************************************
ok: [localhost] => {
    "msg": "Task is running"
}

PLAY RECAP ****************************************************************************************************************************************************
localhost                  : ok=5    changed=0    unreachable=0    failed=0

tasks.yml

- debug:
    msg: Task is running