Have you tried the Sunday Riley Good Genes? https://www.gofriendshop.com/products/sunday-riley-good-genes-all-in-one-lactic-acid-treatment 28
It's one of their breakout products that put them on the scene as a leading skincare brand! It's got licorice and lemongrass which have properties that reduce dark spots and acne scars. I've heard great things about Sunday Riley Good Genes for brightening.
Another ingredient you can look at is Kojid acid with limits the overproduction of melanin, which is what contributes to dark spots. It's also a natural ingredient! https://www.gofriendshop.com/products/dr-dennis-gross-skincare-clinical-grade-ipl-dark-spot-correcting-serum35