Resizing full-screen apps often fail if app is started from subprocess

Hi
I am starting my full-screen prompt-toolkit application in a independent python process created by the subprocess module.
But it seems that this messes with proper rendering of full screen apps. The same text can get written twice and lines are not the proper length etc. It seems to fail more often as the terminal window gets bigger.
Tried PowerShell but same problem. Seems to work as intended if not started in a subprocess. Any ideas?
I am using Windows 10 Enterprise (1909)
Example using the calculator full-screen example app.

from subprocess import call
import calculator

if __name__ == "__main__":
    startstr = f'start /max cmd.exe /c python {calculator.__file__}'
    call(startstr, shell=True)

Reproduce the calculator full-screen example from the issue on Windows 10, comparing direct execution with the shown subprocess call and shell command. Start by tracing the calculator example and subprocess launch behavior; done means full-screen output has no duplicated text or incorrectly sized lines when the terminal is resized.