UserAgent: Mozilla/5.0 (X11; CrOS x86_64 10718.4.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.4 Safari/537.36
Platform: 10718.4.0 (Official Build) dev-channel eve

Steps to reproduce the problem:
1. Attach UHD monitor to Pixelbook (USB-C to HDMI-2)
2. Set display to 3860x2160 60 Hz
3. Colors are bright and washed out

What is the expected behavior?
Colors should be the same as if the monitor is set at lower resolutions. This works fine on stable channel, I just updated to dev for Crostini and discovered this problem.

What went wrong?
Colors are bright and washed out. Display is unusable like this. I'll attach two photos, one is 1920 resolution with proper colors, the other is 3840 resolution with incorrect colors. These are photos, not screenshots, because screenshots don't show the problem.

Did this work before? Yes 

Chrome version: 68.0.3440.4  Channel: dev
OS Version: 10718.4.0
Flash Version: 

Tried all mixes of color-related flags, including resetting all and disabling night light.
 

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