Which system DLL in Windows 10 is responsible for the standard scrollbars?

With implicit reference to my previous (and pretty un-answered) question about the well known and annoying “snapback effect”:

• https://stackoverflow.com/questions/79261291/any-solution-for-windows-scrollbar-snapback-effect

Considering that, missing any official support from Microsoft and any third party patch, I am considering to eventually proceed to reverse engineering and patching, my question is: Which Windows 10 system DLL contains the code for computing the standard scrollbars, and which is therefore responsible for the unwanted “snapback” effect?