In the audit history, you can choose to display 'System Updates'. These are changes that Flow makes in the background, often in response to another user action.
Generally speaking, you won't care about these "behind-the-scenes" updates. So, by default, we hide these updates from your audit trail. But they can be helpful if the Flow team needs to investigate a data issue on your account.
To enable System Updates, check the box that says 'Include System Updates'.
When enabled, you may see some entries with the Flow logo (like the one below), these are system updates.