are you sure your demo is working properly? Native D3D11 on AMD looks like this:
Actually, yeah, this is a bug in your demo. Shader I/O isn't compatible between stages since matching is not done via semantics but rather by register index, and the register indices don't match because PS is missing the position input.
Changing it to
"float4 main(float4 pos : SV_POSITION, float2 texCoord : TEXCOORD) : SV_TARGET {"
is the proper fix here. I think what's happening on WARP/wined3d is similar to DXVK 2.x behaviour where it reads your texture coordinate from the raw position output, but not actually your texture coordinate, which is also why the pattern is flipped.
Nothing extracted yet.
I'm running a simple D3D11 example which proceduraly generates a texture, uploads it and then samples onto a quad.



DXVK produces solid gray rectangle:
WINED3D works fine:
WARP also produces expected result in Windows:
Software information
d3d11-srv.cpp
System information