[Python] What is the reason for the error message: error: externally-managed-environment?...

Context:

• MacOS Ventura 13.6.7
• Homebrew installed

Error message:

user@go-2 Oximeter % pip3 install pyserial
error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try brew install
xyz, where xyz is the package you are trying to
install.

If you wish to install a Python library that isn't in Homebrew,
use a virtual environment:

python3 -m venv path/to/venv
source path/to/venv/bin/activate
python3 -m pip install xyz

If you wish to install a Python application that isn't in Homebrew,
it may be easiest to use 'pipx install xyz', which will manage a
virtual environment for you. You can install pipx with

brew install pipx

You may restore the old behavior of pip by passing
the '--break-system-packages' flag to pip, or by adding
'break-system-packages = true' to your pip.conf file. The latter
will permanently disable this error.

If you disable this error, we STRONGLY recommend that you additionally
pass the '--user' flag to pip, or set 'user = true' in your pip.conf
file. Failure to do this can result in a broken Homebrew installation.

Read more about this behavior here: <https://peps.python.org/pep-0668/>

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

[notice] A new release of pip is available: 24.0 -> 24.2
[notice] To update, run: python3.12 -m pip install --upgrade pip



Why is this error message returned? I ask because on I do not recall seeing this on my other Homebrew Macs that have pyserial installed.

I was successful with a virtual environment, however, I would like to understand the nature of the error: I would think pip3 install pyserial should install to the system python without error

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