Since windows 10 introduced the dark theme, more and more apps go along with the theme, and that includes their title bars. Even file explorer has it now. But Neovim-qt always has a white title bar, regardless of the OS theme or the vim theme. I use it fullscreen not to see the title bar but it'd be nice if it went with the surrounding colors even when it's not maximized.

P.S. if the setting to color title bars is on, it gets the accent color, not white.