The tarball posted to GitHub with the 5.0.1 tag identifies itself as version 0.0.1, as shown below:
conjecture:/tmp/tmp.01y9E7kIbR% wget -q https://github.com/corydolphin/flask-cors/archive/refs/tags/5.0.1.tar.gz
conjecture:/tmp/tmp.01y9E7kIbR% tar zxf 5.0.1.tar.gz
conjecture:/tmp/tmp.01y9E7kIbR% cd flask-cors-5.0.1
conjecture:/tmp/tmp.01y9E7kIbR/flask-cors-5.0.1% grep '^version' pyproject.toml
version = "0.0.1"