AMD gpus have "Adaptive Backlight Management" which reduces your screen's backlight but then tweaks the colors to compensate. For example, my laptop's backlight is set at 33% but with abm it reduces my backlight to 8%. Personally I don't even notice it is on / my screen seems just as bright as before, but when I first enabled it I did notice some slight difference in colors so its probably not suitable for designers/artists. I'd 100% recommend it for coders though.
Strangely, Apple seems to be doing the opposite for some reason (Color accuracy?), as dimming the display doesn't seem to reduce the backlight as much, and they're using a combination of software dimming, even at "max" brightness.
Evidence can be seen when opening up iOS apps, which seem to glitch out and reveals the brighter backlight [1]. Notice how #FFFFFF white isn't the same brightness as the white in the iOS app.
The max brightness of the desktop is gonna be lower than the actual max brightness of the panel, because the panel needs to support HDR content. That brightness would be too much for most cases
This was a photo of my MBA 15" which doesn't have an HDR capable screen afaik. Additionally, this artifacting happens at all brightness levels, including the lowest.
It also just doesn't seem ideal that some apps (iOS) appear much brighter than the rest of the system. HDR support in macOS is a complete mess, although I'm not sure if Windows is any better.
