If you are sick and tired of display auto changing brightness even when you disabled the ambient light sensor and adaptive brightness in power settings in advanced power plan options, you still got some stuff to disable.
Open Intel Graphics settings and go to Power options. You may also access them from that advanced power plan options. Select maximum perfomance. That’s it, dynamic contrast is turned off. Don’t forget to turn it off for battery mode if you are on a laptop. This works for Intel. Other graphic cards may have different settings.