What color change is often seen when light passes through Interstellar Extinction dust?

The light is often reddened.

When starlight traverses massive clouds of interstellar dust, this particulate matter absorbs and scatters the light along its path toward Earth. This scattering process is not uniform across the entire spectrum; the dust particles preferentially scatter shorter, bluer wavelengths of light more effectively than the longer, redder wavelengths. Consequently, the light that successfully penetrates the dust cloud and reaches the observer has had much of its blue component removed, resulting in the observable phenomenon where the remaining light appears distinctly reddened—a key diagnostic clue for identifying such extinction events.