I work on a laptop with an external display, and I recently tried moving it from side-by-side to top-and-bottom. I like the ergonomics, but it breaks Fitt's Law by removing the "infinite edge" that menu bars rely on. Picking out individual browser tabs at the top of my bottom display is a particular difficulty, as is hitting the Windows toolbar at the bottom the top display.
I dimly remember using a Linux desktop window manager that introduced a "bump" between monitors to solve this, your cursor stopped at the edge between displays unless you approached it with sufficient speed to overcome "inertia". I found a bunch of articles about MouseMonitorEscapeSpeed on Windows but it looks like that might have been phased out around Windows 10 (I'm on 11 now), and anyway most of the content is people who don't want a "speed bump" and are trying to get rid of it.
My preference would be to reintroduce this inertia between displays, either as a registry edit or with 3rd party software. Making the browser tab-bar taller would also help, and honestly I'm open to any suggestions from people with similar problems.