Does the following event trigger the de-provisioning of a user's access?

Yes, when the user's application access is governed through attribute-driven role assignment, a department change can trigger deprovisioning of access that is no longer appropriate. Identity Security Cloud roles can use mapped identity attributes such as Department as membership criteria. During identity processing, SailPoint evaluates whether the identity continues to satisfy those criteria.

If the user moves to another department and consequently ceases to satisfy the role's assignment criteria, the identity is removed from the role. SailPoint explicitly documents that when identities are removed from roles because of assignment-criteria changes, access assigned by those roles is removed or deprovisioned , unless the same access is independently provided through another role or assignment.

This implements birthright and role-based lifecycle governance: business changes such as department transfers should automatically cause obsolete access to be removed while new access appropriate to the destination department can be provisioned. SailPoint even provides a workflow template specifically addressing identity department changes and reassessment of old versus new access.

Thus, a department change is a valid deprovisioning trigger when the former application's access derives from criteria that the identity no longer satisfies.

Study Guide Reference: Provisioning — Automated Role Assignment, Attribute Changes, Role Deprovisioning and Department-Based Access Lifecycle.