HDR and color management in KWin, part 3
Quoting: HDR and color management in KWin, part 3 | Xaver’s blog —
This is however not convenient to change quickly and doesn’t apply to HDR content, which so far is always presented at 100% brightness. In Plasma 6.1, you’ll be able to use the same ways to control brightness as on laptops or with displays that support DDC/CI in SDR mode: Just drag the brightness slider, press keyboard shortcuts or scroll on the brightness icon in the system tray, and it’ll dim the whole screen like you’d expect.