iATKOS | United Kingdom

I successfully updated my MacBook Pro and I’m currently trying to update my work 2012 Mac mini, I got the installation on, but the Mac is not displaying on my screen properly, pic attached.

It’s 1000% the screen because if I change the aspect ratios the section that currently looks bad looks perfectly fine, I’ve downloaded better display app, and have been messing around with it, but still cannot get it to work properly? Anyone have any advice?