ShaderEffectSource/layer always accounts for high DPI in textureSize, cannot work with pixels (Incorrect image when layer.enabled is true)

Setting layer.enabled to true warps the displayed image.
To reproduce:
1) Run the attached example
2) layer.enabled is false, Bayer pattern is visible.
3) Set layer.enabled to true -> no Bayer pattern visible anymore.
There should be 3 texels between each black line, but when the layer is enabled there are 4 texels. Total number of texels silently changes from 128 to 160.

The problem is not reproducible only if "Display Scale and Layout" is set to 100% in the system settings.