Picom has an awesome feature [0] that, for the sake of all our eyes, should come by default on every device with a screen. It can continuously adjust the brightness of individual windows by averaging all the pixels in that window. It's great for defending against "flashbangs" (when a new tab burns your eyes with a blank white screen).
0: https://github.com/yshui/picom/blob/ae73f45ad9e313091cdf720d...