Python was not found after closing commandline. Windows opens app store when I type python

I have downloaded and installed python from here.

Then I restarted and opened a commandline and typed

python --version

I recorded all my actions, so I can post a screenshot of that:

It works and shows the version number.

Then I performed the following steps to install Jupyter because I want to use a local runtime with Google Colab:

In the Windows commandline (not in the Python window!!), I type this:

pip install virtualenv
python -m pip install --upgrade pip
virtualenv opencv (I guess I can choose a random name here because we will not be using OpenCV, right? But for simplicity, I keep this name now)
I CD to c:usersMYUSERNAMEopencvScripts
activate.bat
pip install numpy
python -m pip install jupyter

Now my browser opens this page: http://localhost:8888/tree
Now I click "New" and "Python 3 (ipykernel)"

Now I want to install the extension jupyter_http_over_ws.
I type:

pip install jupyter_http_over_ws

Nothing shows up when I type text on the keyboard. It looks like this:

Because I want to be able to type again, I close the command line and open it again.

Now I type again:

pip install jupyter_over_http_ws

It says

The command "pip" has been misspelt oder was not found.

Because I have no idea what is happening, I type:

python --version

I am expecting that it shows the version number like before.

But instead it shows

"Python was not found."

Why is that?

ps: When I type "python", it starts the Microsoft App Store and offers me to download it:

Thank you!