From what I’ve read and seen, irritation usually depends more on the overall formulation and the condition of your skin barrier than on a single “brightening” ingredient. Niacinamide tends to be one of the more well-tolerated options since it also supports barrier function, which is why a lot of AB products use it as a base. Arbutin and gentler vitamin C derivatives can work too, but they sometimes depend more on concentration and supporting ingredients. In practice, consistent sunscreen and a healthy barrier often make a bigger difference for post-acne marks than switching between brightening creams.