Niacinamide (nicotinamide, a form of vitamin B3) is a widely used and generally well-tolerated skincare ingredient. Water-soluble and compatible with many formulation types, it appears in serums, moisturisers and cleansers alike.
It is chosen to support the skin's overall appearance and comfort, and features often in barrier-friendly approaches because it is usually tolerated well even by sensitivity-prone skin.
What matters is concentration and the formulation as a whole — no single ingredient is a "miracle". Introduce new actives one at a time and observe your skin's response. Consult a physician for choices suited to your skin.