We don't make the rules. We make every effort to bend them to your benefit, though.
Dark Mode is not just Automatic—that your Mac can change with the clock—but automatic that Big Business 14 uses the system colors, and all windows and their contents now change when they change.
Dark Mode matters even if you never use it! Big Business 14 is updated to use System Colors, which change by themselves. If you use Light Mode, you use System Colors.
As a result, custom shading that Big Business used, like gray backgrounds for locked fields, were replaced with automatic colors. This is suboptimal since it undermines intutive design.
Updates to Big Business 13 have ended, so it now possible to update custom colors in Big Business 14 without consequence.
Actually, that is not entirely true. The consequence will be that if you install Updates, things will continue to change.
These changes are minor, shading an non-enterable field, but consequential because they make each screen more intuitive.