Hi @rufusbecker
I did this plugin a little over year ago: GitHub - ajnyga/hideEditorOwnArticles: Plugin for Open Journal Systems 2.4x. If one of the journal editors have submitted an article of their own, this plugin will hide all review related information regarding that article.
However, this is a problem that can not be solved 100%. There are always loopholes that an editor can use simply because the editor can use functions like “login as” or create new user accounts (for example a new editor account).
The complete solution would probably need some major changes to the whole OJS software, but the bottom line is, I think, that you almost always need an user account that can do anything. This is one suggestion on how to solve this: New role (permission level) to to solve a central problem in OJS