On Windows, the mouse scroll wheel in Browse mode used to be equivalent to clicking the navigation arrows. This is a Good Idea that our users expect. When I use the scroll wheel I'd expect the records to scroll, as has been the case in all previous versions of filemaker.
The behaviour is correct for list and table view and should carry forward to form view.
If backward compatibility is a concern, you could offer this as a file preference. Or if you want to make us work harder, you might create an OnScrollWheel script trigger so we could intercept the wheel and defeat it.