What happens when a person moves to another team, or when a manager is replaced by someone else. Who can see whose reviews?

A new manager can always instantly see every performance review (even historic ones) of all people reporting to her either directly or indirectly. In addition, a manager can always see reviews they signed for previous team members (so no matter if the manager leaves the team or the team member, the review is still accessible to the "old manager". 

Learn more about the details on the user management documentation.

The new manager will be able to edit an existing performance review in an open cycle. Before the new manager makes adjustments, the old manager's name will appear on the review. In order to have the new manager's name appear, they'll need to edit the review.