External display color changes when MacBook lid is closed

Solution 1:

I had the same problem. My external monitor doesn't support HDR, so PaulVO's method didn't work for me.

As Nimesh suggested, I unchecked the "True Tone" for my Mac retina display. I immediately saw my Mac display had the same blue tint. Then I was able to calibrate both the color of my Retina display and external monitor. Somewhere between D50 and D65 works best as qrius suggested.

Thank you all for the inputs!

Solution 2:

If you update to macOS 10.15.4 it may now detect that you have a HDR screen, and makes your external screen colors look weird.

To fix this:

• Go to Display settings
• Uncheck "High Dynamic Range" for your external display
• Everything should be back to normal.