I have encountered a visual/window management bug in Zorin OS 18.1 Core while customizing the panel.
When I enable "Panel Intellihide", full-screen applications or windows do not render correctly. As soon as a window goes full-screen, it gets clipped or zoomed in from the top-left corner, and the edges of the window are cut off. I can only fix it temporarily by scrolling with my touchpad inside the application.
Steps to Reproduce:
Open Taskbar Settings, then Style.
Turn ON "Panel Intellihide" (with custom opacity/margins or even default settings).
Maximize or full-screen any application (e.g., Files, Browser, VS Code).
The window instantly clips/zooms in and cuts off from the top-left.
Turning Panel Intellihide OFF completely fixes the issue. I have also tried toggling options inside the Intellihide gear menu (like "Focused windows" to "Maximized windows" and unchecking "Overlapping"), but the bug persists.
I have Intellihide enabled, too but don't have the same Issue like You. To understand me wrong: I don't want to say there is no Issue.
Did You tried it with switching between Wayland and Xorg? You can do that on the Login Screen. click there on Your Profile so that the Password Field appears. When it is appeared, You should see in the bottom right Corner a Gear Icon. click on it and you should see 2 Options. switch between both to see if it behaves the same.
You posted Your Hardware Specs here:
But there is not Graphics Card mentioned. Do You use the iGPU from the Processor or do You have a dedicated Graphics Card?
Also: How are Resolution and Refresh Rate set up? Do You have Fractional Scaling active?