Debian
... is not something you should ever use on a desktop PC. Due to its eternally very outdated nature and not even shipping bugfix updates**** it is not a good fit for anything but servers.
Wayland, for some reason, couldn't handle 4 monitors, with one above the other three.
"Wayland" doesn't handle monitors at all. What (because of Debian, wildly outdated) desktop did you use?
Oh, and the biggest issue I had with Windows was copied straight into Linux. I want my (single) taskbar on a monitor that isn't my primary.
Not a Linux issue, but a problem with the desktop environment you chose. KDE Plasma allows you to configure panels in any way you want.
Stop using Xorg and your scaling problems are gone.