Why does my external monitor brightness increase on 144 Hz? I have an external display connected via DisplayPort.  With 144 Hz refresh rate selected the image brightness goes up by quite a bit.  Any other refresh rate (even 120) will show a darker, less washed out image.  The actual monitor OSD settings are not changed when this happens.  Anyone know why this would happen and if it can be prevented?
Turns out this was related to another issue I had, caused by a monitor with defective timing.  I got a replacement which solves this.