Microsoft has been fixing Windows 11's annoying white flash bug in File Explorer for over 2 years

The latest Windows 11 preview build mentions a fix for File Explorer that should stop it from flash banging you in dark mode.
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Windows 11 25H2 gets faster File Explorer with improved context menus, and more in new build

Microsoft is rolling out a new Windows 11 preview build in Dev/Beta channels, offering users the chance to try improved context menus in File Explorer, the new full-screen Xbox experience, and more.