The Light one is the out-of-the-box set theme. Windows 11 by default comes with four Themes to set – Windows (light), Windows (Dark), Glow, Captured Motion, Sunrise, and Flow.Now, on the corresponding right side panel, you will see the Themes-related settings.Select the Themes option from the left side panel menu.
Windows 11: Install themes from the Microsoft Store Change Windows 11 Default Theme