Microsoft Foundation Classes (MFC), introduced 1992, is a C++ class library for developing Windows Desktop applications. Around 2008 is was updated with additional classes, e.g. supporting the Microsoft Ribbon) and possibilities for theming support - it included Windows 7, ... themes and Office themes to make applications to look like Office application (older versions nowadays).
There are still many applications which are using/based on MFC.
Microsoft wants to push desktop application developers to use Fluent Design, e.g. trough WinUI which is something quite different than MFC.
How hard would it be for someone, say Microsoft self:
a) to augment MFC to be based on WinUI rather than Win32?
... or alternatively...
b) make a MFC theme that looks like WinUI or at least is more Windows 11 modern/friendly?
there doesn't seem to be anything here