I've had better luck with fractional scaling on Windows over Linux. Can be hit or miss if any given Linux application will handle fractional scaling well, but the desktop environment (KDE Plasma on Ubuntu) does fine with it.
My experience with it and multiple screens is not great.
Not sure why it is that way - it's just a matter finding a global pixel size, rendering all screens to these bitmaps and then 2D scaling them down to panel resolution.
