It wouldn’t be such an issue if each OS didn’t have several design languages.
Windows has 10 different design languages all still there in the OS. It should have stuck with MetroUI, Fluent is an eyesore in my opinion.
MacOS can’t keep things consistent to save itself.
And Linux has KDE/Breeze and Gnome/Adwaita competing, with the older Windows 95 imitations still around.