MacOS brightening only a part of the screen

As I understand it's more of a feature than a problem, but I don't get it where it comes from. I noticed that in several places (e.g. hovering on a YouTube video thumbnail or inside a YouTube video) they brighten I'd guess to the maximum brightness, while all the other things on the screen stay the same as set brightness. Is it possible to manage this feature?

MacBook Pro 14"