It’s barely a UI skin! It’s not even complete or self-consistent, and the original Win10 skin is still there under it, feature-complete. People noticed that certain boot failures of Win 11 bring back the original Win 10 look!
It’s basically a “Mac mod” for Windows made by a bunch of Apple users working within Microsoft.
Well, in Windows 10 there's at least 4 different styles of context-menu in the Taskbar depending on where you click - so given that, I'm guessing it's a bit of a mess.
1. Right-click the Start button or empty space on the Taskbar: Win32 (USER32?) standard menu, but with a custom dark background and extra menu-item padding to make them touch-friendly. Earlier versions of Windows 10 used standard white menus with no extra padding. Uses the standard Windows menu font (Segoe?).
2. Right-click a pinned program icon: Aero Glass-effect jumplist menu with very smooth opening animation (seems to be the same UI framework as the Start Menu itself). Uses the standard Windows menu font (Segoe?).
3. Right-click a jumplist item: an opaque sub-menu that uses a much larger font-size, and I think a different typeface too. If the jumplist menu item is a shell object then this context menu will contain some (but not all) of the registered custom shell-wide menu items as in File Explorer and other views.
4. Right-click a window thumbnail: you get the window-menu for that window, which (on my computer) uses the standard Windows grey background and different font-sizes and metrics to all the other menus.
5. Right-click a custom Rebar[1] / Toolbar control in the Taskbar (I think they removed this feature from Windows 11?): you'll get whatever custom menu the author of the Rebar control decided to use.
6. Right-click an icon in the ("system tray") notification area (as opposed to the Action Center): as with Custom Rebars the menu style you get depends on the application - though tellingly different built-in standard/system Windows icons have different menus, e.g. right-click "Safely remove hardware" gives you a grey menu, but right-click the Volume icon and you'll get a black menu.
[1] https://learn.microsoft.com/en-us/windows/win32/controls/reb...
I’d throw it out and rebuild it to make it reliable and defensive against broken applets.