It just started doing this today, every few minutes my monitor brightness or colour adjusts slightly and it's very distracting. I have 'Automatically adjust brightness' turned off in the display settings.

Is this some new feature? Is it possible to turn it off? This is a 2019 macBook Pro running Big Sur 11.6 if that helps. This is happening to all of my monitors, one is an AOC I2276VWM and one is an Acer.

  • Did you check the cables (and maybe replace/switch them)?
    – nohillside
    Commented Oct 25, 2021 at 11:47
  • I've tried the same cables and monitor on a Windows machine and they work fine so I think this is a Mac issue.
    – gloofm
    Commented Oct 25, 2021 at 12:47

1 Answer 1


macOS doesn't have any way of controlling the brightness of external monitors, that's only possible with third party apps that use DDC (Lunar, MonitorControl, DisplayBuddy) or dimming apps (Lunar Lite, QuickShade, f.lux).

If you're not using any of the above apps, then it's possible that you're noticing the effects of True Tone.

If disabling True Tone doesn't fix this, then it can be an incompatibility between the MacBook GPU and the monitors (although that's unlikely given that you notice the problem on two monitors of different brands).

Once you’ve ruled in compatibility then a defective cable or hardware on the display or Mac side are the cause of this.


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