They probably fixed it now, but this is what Microsofts own explorer looked like in 2018 with Dark Mode:
https://www.howtogeek.com/fyi/microsoft-adds-a-dark-theme-to...
You can guess about the support in third party apps.
https://i.imgur.com/jVM9dUA.png
As an example these days the Windows OS includes Microsoft apps that are built using the QT toolkit (OneDrive). That’s the example developers follow.
They probably fixed it now, but this is what Microsofts own explorer looked like in 2018 with Dark Mode:
https://www.howtogeek.com/fyi/microsoft-adds-a-dark-theme-to...
You can guess about the support in third party apps.