"dim wallpaper" has no effect

Toggling this setting doesn't appear to do anything for me. By my eye, the wallpaper is always dimmed, whether the setting is on or off. I would love it if I could turn it off and have the wallpaper be more vibrant.

To reproduce:

1. Set a wallpaper (I usually apply some theme)

2. Notice the wallpaper is dimmed

3. Toggle the “dim wallpaper” setting to off

Expected: the wallpaper gets brighter

Actual: the wallpaper doesn't change