> If you don't use activate.bat, but just run the venv's python directly, what do you see? I get:
> What shell are you using? Above is with cmd.exe.

I get the same result as activating (i.e. shows the base interpeter). All results in cmd.exe as well.

> If you "echo %PATH%" after activate.bat, what do you see?
> Before running activate.bat, do you have a python.exe in your path? If so, is it the one that subprocess is reporting?

PATH is as expected, the venv’s Scripts directory at the front after activation. I (only) have a python.exe from Windows Store in PATH. The one reported by subprocess is not in PATH.

I’ll try to find a clean machine (maybe a VM) and try whether I can replicate this. BTW the problematic versions for me was 3.7.5 and 3.8.0.