pip3 vs pip issues in building a python wheel

I'm trying to build a simple *.whl file according to the docs:

$ python3 -m pip install --upgrade build # <--- success
$ python3 -m build                       # <--- failure 
* Creating virtualenv isolated environment...
* Installing packages in isolated environment... (setuptools>=61.0)
<... omitted for brevity ...>
/tmp/build-env-y4zgw72t/local/bin/python: No module named pip
ERROR Command '['/tmp/build-env-y4zgw72t/local/bin/python', '-Im', 'pip', 'install', '--use-pep517', '--no-warn-script-location', '-r', '/tmp/build-reqs-ioy8d055.txt']' returned non-zero exit status 1.

I usually get away with pip3 instead of pip ... until now (?)

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(pyproject.toml file is from the documentation)

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