In which scenarios does the “Performed By” value appear as Application instead of a user?

We encountered a case in the Production environment where a Requester created a requisition and submitted it for approval.
The same user is also the manager assigned as the first approver in the approval flow.
The requisition is for an existing supplier with a new site.
According to the Document History, the requisition was cancelled, but the “Performed By” column shows Application
We were not able to reproduce this behavior in lower environments.

Question:
In which scenarios does the “Performed By” value appear as Application instead of a user?
Is this expected behavior for system-driven validations or automatic cancellations (e.g., currency or setup issues)?