Whether you choose a black or brown mascara depends on your individual style and possibly also on the occasion. If you want a really expressive look and intense gaze , then black mascara is of course still the classic choice. It puts the focus on the eye area and gives the eyes depth and definition.
If you want a very soft no-makeup look for everyday life that only gently and subtly emphasizes your look, or if you generally have a very light skin and hair type for whom black mascara quickly looks too unnatural and harsh for everyday use, then you can definitely use a brown mascara . Since the color contrast between the brown mascara on your eyelashes, the skin and the eyes is usually less, the eye area can appear softer and the face can appear more delicate and fresh overall.
You can't go wrong when it comes to eye color. Both versions harmonize with all eye colors.
The combination of both colors is also great. Use a black mascara to emphasize the upper lashes and open up the eyes, and use a soft brown tone for the lower lashes to maintain the lightness there.