There are four “Color Themes” or levels of brightness that you can choose to display Photoshop’s interface. By default, the second-to-most dark theme is selected. You can change the theme by clicking on the color swatches in Preferences > Interface > Appearance, or use the shortcut Shift + F2 to move to a lighter color theme or Shift + F1 to cycle to a darker theme. Note: depending on your keyboard, you might have to add the function (fn) key).
I prefer the default interface as it allows me to focus more on the image and not the interface. Plus, it’s easier on the eyes to look at a darker screen all day.
My free video from LinkedIn Learning (Customizing the Photoshop Interface), steps through changing the Color Theme (starting at 1:35).