While you may receive an email notification about any new FLAGS feedback that a faculty member has provided for you, typically from the Registrar's Office or academic advising office, you don't need to wait for such notifications. You can start checking your feedback yourself through the FLAGS Early Alerts Tile in One.IU. If you don't have any in a particular class, nothing will display.
The above tile will navigate to your My Grades section of the SIS Student Center. There you will find the Performance Roster section, as is shown below.