Version: 4.2.7-beta1 (git 963916b)

SUMMARY
the Color Selector accessed by the holding 'Ctrl' shortcut while the Brush Tool is selected is unaffected by the 'sample all visible / current layer' settings in the tool options of the color selector tool.

STEPS TO REPRODUCE
1. create a fill layer with a light value and set it to some non-normal blending mode (tested multiply + overlay)
2. create a paint layer underneath the first. paint a few patches of color.
3. with the 'sample current layer' option selected in the tool options of the Color Select Tool, compare result of sampling and repainting the colors on the paint layer with the brush tool shortcut and tool versions of the color selector.

please see attached file if unclear.

OBSERVED RESULT
the colors re-sampled with the shortcut are different from the original sampled color (are being affected by the layer above).

EXPECTED RESULT
expected both the shortcut and the tool version of the Color Selector to yield the same result (and be unaffected by the layer above).

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

Krita
  Version: 4.2.7-beta1 (git 963916b)

Qt
  Version (compiled): 5.12.5
  Version (loaded): 5.12.5

OS Information
  Build ABI: x86_64-little_endian-llp64
  Build CPU: x86_64
  CPU: x86_64
  Kernel Type: winnt
  Kernel Version: 6.1.7601
  Pretty Productname: Windows 7 SP 1 (6.1)
  Product Type: windows
  Product Version: 7sp1


OpenGL Info
 
  Vendor:  "NVIDIA Corporation" 
  Renderer:  "GeForce GTX 660/PCIe/SSE2" 
  Version:  "4.5.0 NVIDIA 355.60" 
  Shading language:  "4.50 NVIDIA" 
  Requested format:  QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
  Current format:    QSurfaceFormat(version 4.5, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples 0, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 1, colorSpace QSurfaceFormat::sRGBColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
     Version: 4.5
     Supports deprecated functions true 
     is OpenGL ES: false 

QPA OpenGL Detection Info 
  supportsDesktopGL: true 
  supportsAngleD3D11: true 
  isQtPreferAngle: false 
== log ==
 Supported renderers: QFlags(0x2|0x4|0x8) 
Surface format preference list: 
* QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    2 
* QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    4 
* QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 16, greenBufferSize 16, blueBufferSize 16, alphaBufferSize 16, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::scRGBColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    2 
* 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) 
    2 
* QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 16, greenBufferSize 16, blueBufferSize 16, alphaBufferSize 16, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::scRGBColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    4 
* 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) 
    4 
* QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    8 
* QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 16, greenBufferSize 16, blueBufferSize 16, alphaBufferSize 16, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::scRGBColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    8 
* 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) 
    8 
Probing format... QSurfaceFormat::DefaultColorSpace 2 
Found format: QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::CompatibilityProfile) 
    2 
 
== end log == 

Hardware Information
 Memory: 7 Gb
 Cores: 4
 Swap: C:/Users/abcd/AppData/Local/Temp