atal: [10.21.21.11]: FAILED! =>                                                                                                                                                                                   
  msg: |-                                                                                                                                                                                                          
    The task includes an option with an undefined variable. The error was: 'ansible.vars.hostvars.HostVarsVars object' has no attribute bla bla

Check the names in group_vars! They need to match the name of the group in the inventory file.

• Ansible debug one variable
• Ansible debug all variables