Color changes with laptop screen open vs closed

[awesterink]

I am using a Dell 3415W UltraWide screen (3440x1440) scaled down to 80% using BetterDisplay 1.2.9. I use the Dell as my main screen, with my M1 MacBook Pro as a 'sidekick' screen for stuff like chat, calendar etc. I noticed that if I leave the screen of my M1 MacBook Pro open, the color temp on the external Dell display is somewhat warm. When I close the MacBook display, the color temp of the external Dell display switches to a very noticeable cooler temp. What could be causing that? Is this something I could influence with BetterDisplay?

[waydabber]

Hi @awesterink - this is the true-tone feature. It is active only when the lid is open but it affects external displays as well. You can disable it in macOS and in BetterDisplay as well (Tools/System Colors/Enable True Tone).

[awesterink]

Yessir, that does the trick. Thank you!

[kolorfilm]

Would be great if this True Tone can be enabled per Screen (not only in general). It seems it works fine on some screens but my external Dell 3223Q is too warm with True Tone.