MacBook screen (wallpaper) cut

It's very strange that it only affects the wallpaper area but not the menu bar... Are you running the latest version of macOS Big Sur (11.4)?

Did you try connecting the computer to an external display to verify if the problem also replicates there?

What happened if you start your computer in Safe Mode? (turn on and inmediatly hold the Shift button until you see the Apple logo with the progress bar)

OK,

Are you still having the problem even with the latest versión of Big Sur?

You probably need to get an appointment with Apple or an AASP, it could be a Display related problem or something with the GPU located in the Logic Board.

Picture above is from the same MacBook you shown in your first post? Because in the first photo you can easily see that the menu bar is not affected...

It affects the menu bar too, i tried the safe opening same thing and i’m waiting for the latest big sur to install

Yess its the same, it depends on the wall paper, when i change it , it affects more or less