It's likely because of
#52b7388.
Try to solve it as the workaround suggest. You can downgrade the library using:
pip install protobuf==3.20.1
Since this is a runtime error, you should probably create a virtualenv before/after doing this so that subsequent installs of completely unrelated packages don't alter the
protobuf version that you installed manually. It can happen e.g. if you install a lot of python-based programs e.g. youtube-dl or you have a Python environment such as Anaconda.
Something like this, since you're installing & running Electrum from the command-line:
python3 -m venv electrum
source electrum/bin/activate
<install electrum & protobuf, and run electrum here>
deactivate # To get out of the virtualenv - just `deactivate` works.