They aren’t real. At least not for traumatic events they’re not. Trauma has a tendency to make you not be able to forget the traumatic event, in extreme cases these events are so easily remembered they induce panic/ fight or flight, I believe this is considered the mechanism behind PTSD.
I did a psych grad program and the concept of repression was discussed as dangerous, incorrect pseudoscience. That was a few years ago and not my specific area. Hopefully a cognitive / memory expert can jump in here.
My half assed attempt at getting a citation for my claims: