SUMMARY
Because of bug 412881 it is nearly impossible (and I don't use this word lightly) to work with Krita's HDR on Yoga c940 without making the brightness of the screen higher. But then the HDR canvas gets brighter as well, showing incorrect colors and artifacts.

STEPS TO REPRODUCE
1. Make sure your system is capable of displaying HDR.
2. Open Krita using the lowest brightness of the screen. The interface is dark, but the canvas shows correct colors.
3. Change the brightness of the screen to be higher.

OBSERVED RESULT
The HDR canvas is getting brighter, shows incorrect colors and artifacts.

EXPECTED RESULT
The HDR canvas looks the same as before.

ADDITIONAL INFORMATION
I believe system tells applications like Krita incorrect HDR max value. Maybe there is a way to overwrite this, let the user set the value on their own? It could show the value system tells it, so the user could just check what value it says when the brightness is lowest, and then copy it to the overwriting field so Krita will always use that value instead of whatever system tells it to.


SOFTWARE/OS VERSIONS
Krita

 Version: 4.3.0
 Languages: pl, en_US, en, pl, en_US, en, pl, en_US, en, pl, en_US, en, pl_PL, pl, en_US, en
 Hidpi: true

Qt

  Version (compiled): 5.12.8
  Version (loaded): 5.12.8

OS Information

  Build ABI: x86_64-little_endian-llp64
  Build CPU: x86_64
  CPU: x86_64
  Kernel Type: winnt
  Kernel Version: 10.0.18362
  Pretty Productname: Windows 10 (10.0)
  Product Type: windows
  Product Version: 10

OpenGL Info
 
  Vendor:  "Google Inc." 
  Renderer:  "ANGLE (Intel(R) Iris(R) Plus Graphics Direct3D11 vs_5_0 ps_5_0)" 
  Version:  "OpenGL ES 3.0 (ANGLE 2.1.0.57ea533f79a7)" 
  Shading language:  "OpenGL ES GLSL ES 3.00 (ANGLE 2.1.0.57ea533f79a7)" 
  Requested format:  QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 10, greenBufferSize 10, blueBufferSize 10, alphaBufferSize 2, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::bt2020PQColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
  Current format:    QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize 24, redBufferSize 10, greenBufferSize 10, blueBufferSize 10, alphaBufferSize 2, stencilBufferSize 8, samples 0, swapBehavior QSurfaceFormat::DefaultSwapBehavior, swapInterval 0, colorSpace QSurfaceFormat::bt2020PQColorSpace, profile  QSurfaceFormat::NoProfile) 
     Version: 3.0
     Supports deprecated functions false 
     is OpenGL ES: true 

QPA OpenGL Detection Info 
  supportsDesktopGL: true 
  supportsAngleD3D11: true 
  isQtPreferAngle: false