Preview automatically switches to Dark Mode in Full Screen

When I open a document in Preview, the Preview window is opened in Light Mode, respecting my system setting. But whenever I switch Preview to full screen, the window automatically switches to Dark Mode even though my system preference is to use Light Mode.

I've tried searching for a solution online, but most people seem to want to enable Dark Mode, whereas I want to keep it disabled.

How can I make the Preview app respect my system setting?

Your help is greatly appreciated! :)