Using ansible loop until with stdout_lines

I am trying to use ansible loop until the condition is met. I can use until if the output is only single line, however if the output is multiple lines, I will need to use stdout_lines but fail to do so.

If output is single line:

- name: check on sync status
  shell: some command
  register: sync_status
  until: sync_status.stdout == 'SSUS'

If output is multiple lines, then I try to use stdout_lines

- name: check on sync status
  shell: some command 
  register: sync_status
  until: item.stdout_lines == 'SSUS'
  with_items: "{{ sync_status }}"

but I got variable undefined:

fatal: [xxxxxxx]: FAILED! => {
    "msg": "'sync_status' is undefined"
}

I don't want to do it on seperate task because then the sync_status is registered on previous task , and I will be comparing the old status instead of the current status.

Kindly assist.

For example, given the file and the playbook

shell> cat test.txt 
XX

shell> cat playbook.yml
- hosts: localhost
  tasks:
    - ansible.builtin.command:
        cmd: cat test.txt
      register: sync_status
      until: sync_status.stdout == 'SSUS'

the task will fail

TASK [ansible.builtin.command] ********************************************
FAILED - RETRYING: ansible.builtin.command (3 retries left).
FAILED - RETRYING: ansible.builtin.command (2 retries left).
FAILED - RETRYING: ansible.builtin.command (1 retries left).
fatal: [localhost]: FAILED! => changed=true 
  attempts: 3
  cmd:
  - cat
  - test.txt
  delta: '0:00:00.003479'
  end: '2021-06-16 07:27:19.927499'
  rc: 0
  start: '2021-06-16 07:27:19.924020'
  stderr: ''
  stderr_lines: <omitted>
  stdout: XX
  stdout_lines: <omitted>

But, if you insert the string "SSUS" into the file before or during the testing the task will succeed, e.g.

TASK [ansible.builtin.command] ********************************************
FAILED - RETRYING: ansible.builtin.command (3 retries left).
FAILED - RETRYING: ansible.builtin.command (2 retries left).
changed: [localhost]

Fit the parameters to your needs.

Q: "If the output is multiple lines, I will need to use stdout_lines."

A: Test the presence of the string in the list, e.g.

    - ansible.builtin.command:
        cmd: cat test.txt
      register: sync_status
      until: "'SSUS' in sync_status.stdout_lines"