Native Color Temperature toggle does not have the same gamma as setting the color temperature on an sRGB external display

[Sunspark-007]

Your system information

• Steam client version: 1749753892
• SteamOS version: 3.6.24
• Opted into Steam client beta?: Yes
• Opted into SteamOS beta?: No
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

When "Native Color Temperature" is toggled on with an external display connected the expectation is that it should be just what the display has, pass-through.

In actuality, setting the color temperature to 6500K in the deck's display settings and then toggling "Native Color Temperature" on and off, a gamma shift is observed on the external display. With it on, blacks are slightly darker than they should be. With it off, and the deck set to 6500K it is more like what it is expected to be.

Steps for reproducing this issue:

1. In Gwenview advanced settings, uncheck the color management checkbox so that the image is always converted to sRGB. (The monitor here is sRGB and the colour temperature is 6500K or close to it in the "Standard" preset.)
2. In desktop mode add Gwenview to Steam.
3. In gaming mode set Gwenview display properties for resolution to "Native".
4. In gaming mode with "Native Color Temperature" checkbox toggled on open a calibration image and observe the gamma shading.
5. In gaming mode with "Native Color Temperature" checkbox toggled off and display color adjust set to a color temperature of 6500K open a calibration image and observe the gamma shading difference from step 4.