Most brightening products strip you. Acids pull moisture out and leave your barrier compromised, which is why your face feels tight after and looks dull by afternoon.
And a damaged barrier can't hold pigment evenly, so you end up chasing tone while making your skin worse at managing it.
Collagen and hyaluronic acid sit on your face all night alongside the kojic acid. Both jobs, same window. You wake up brighter and plump, not dry and tight.