I think this is a bug in the student notifications processing for mod assign (investigated under 2.6 but appears to be unchanged in master).
When a grader updates a grade in a blind marked assignment (in this case no grade but feedback comments), the student receives a notification through the send_assignment_notification() function in /mod/assign/locallib.php
{$a->username} has posted some feedback on your assignment submission for \'{$a->assignment}\' You can see it appended to your assignment submission: {$a->url}
however if blind marking is still in effect, the $a->username is changed from the $grader object that had been passed.
It becomes the "participant" string and then then the $uniqueidfor user which is the unique id of the submitting user not the grader!
In addition the first and last names of the $userfrom object are also changed to match this.
Given that blind marking at present (AFAIK) is designed to prevent the grader from knowing who they're marking (as opposed to anonymous marking where the graded doesn't know their marker), I think this is a bug
It means the student then receives an email effectively from themselves saying they have updated their feedback, when:
- The student didn't make any change
- The grader's details are now no longer presented to the student
- The student doesn't have any real understanding of who "Participant xxxx" is
- The sender is themselves
However, I'm aware that I could be missing some other facet of blind marking here, so I thought I'd ask before raising it as a bug.