Clean Ubuntu 20 install does not do this. It is because you apt installed python-is-python2. Maybe some other package included it as dependency. btw there is a

Clean Ubuntu 20 install does not do this. It is because you apt installed python-is-python2. Maybe some other package included it as dependency. btw there is also a python-is-python3 package. I would advice you to not use either of them, use virtualenv, pyenv or poetry instead.