@duke6258 Usually we ask you to post "f.lux options > driver info" so we can get a better sense of what's going on. Sometimes this is a driver issue, and sometimes it is the way that the monitors are connected.
@thedoctor2031 yes it is definitely showing here "gamma ramp works=0" for one of the two, which indicates a problem with the video driver. Does it behave differently if you relaunch f.lux?
Edit: it looks like Mac was hiding icon overflow on my top bar on smaller screens. When I connected my computer to an external monitor with a bigger screen, the icon appeared! There may be a way to fix this on the mac side (closing programs in the top bar that aren't flux should be a good start for users who don't have access to a bigger screen), but just wanted to share in case this is helpful to people!
@SteelTalow this is a problem with Windows for a while now, and we have not gotten a fix from Microsoft yet. The decent news is that it only seems to happen once per reboot - so it's terrible but it should be just the one time.
@Arnaud I think you may have encountered a feature that is not ours, but usually from Intel or Windows. You'll want to google "disable Intel DPST" or, if you have Windows 11, you can find an advanced option about changing brightness based on content, and turn it off.