...
Peer reviews are not anonymous, although this option may become available in future.
The date for automatically assigning randomized peer reviews must fall after the due date for the assignment (the default setting must be changed, if only to fifteen minutes later).
Until the availability period for the assignment ends, both the original author and the reviewer can resubmit a file that will overwrite the original. To prevent this, end the availability period at the due date.
If Peer Review is used for Group Assignments, the random assigning of reviews does not take group membership into account (so students might be assigned to review others either in or out of their groups).
When automatic assignment of peer reviews is switched on and a student makes a late submission to the assignment, the student is not automatically assigned peer reviews, even after they have submitted their work. To assign peer reviews to that student, the instructor needs to go to the “Peer Review” menu and either manually assign peer reviews to the student, or click the “Assign Peer Reviews” button.
For further information, see these guides from Instructure:
...