https://www.techradar.com/news/microsoft-takes-a-trip-to-the-dark-side-with-a-new-theme-for-to-do

Dark themes are the new black, and Microsoft is following the trend with a new look for its productivity app, Microsoft To-Do.

The new To-Do theme was spotted by users signed up to Microsoft's Insider Program, alongside an option to use your current Windows theme (which you can set using the Customization control panel).