Recorded video with the viewfinder on :(

Hey everyone!
I am not a videoeditor, but I participated in a shoot where it turns out that the viewfinder was on while filming.

The whole session is shot and I am trying to find out, if there is anyone who knows how or if its possible to fix it - or if the material is completely lost?

Here is a preview 😩
Why is there even a feature like this? And no warning in the camera?