Indeed, this new feature makes Terraform show something that it was previously keeping silent: updating the state to match the remote system.
ignore_changes argument disables Terraform’s behavior of comparing the configuration with the state to plan any necessary new actions, but the “Objects have change outside of Terraform” is reporting a difference between the prior state and the remote object.
Terraform has always been detecting such changes and updating the state to include them, but it was previously silent about it. Being silent about it would means that Terraform could propose to make a change in response to what it detected even though it gave no indication that it had detected anything, and so Terraform is now reporting the updated data it’s using in order to decide what to propose.
The only mechanism Terraform currently has in order to disable detecting changes during refresh is the global
-refresh=false option, which will cause Terraform to not refresh anything at all. If you elect to have Terraform refresh during planning (the default behavior) then it’ll report what it detected in order to be clear about what new values Terraform used as the basis of the plan.