The cadquery-ocp 7.6.3a0 version included a compiled vtk 9.1, which used the tbb12-XXX.dll. This dll had a call to Kernel32.dll for function "GetCurrentThreadStackLimits", and windows7 does not have it. It is only available on Windows 8+.
The offical vtk 9.1 package does not have this depenedency, thus, it can be executed on windows 7.
The old cadquery-ocp 7.5.3.0's tbb dll does not have this function call.
The cadquery-ocp 7.6.3a0 version included a compiled vtk 9.1, which used the tbb12-XXX.dll. This dll had a call to Kernel32.dll for function "GetCurrentThreadStackLimits", and windows7 does not have it. It is only available on Windows 8+. The offical vtk 9.1 package does not have this depenedency, thus, it can be executed on windows 7. The old cadquery-ocp 7.5.3.0's tbb dll does not have this function call.