HTTP: SSL: CERTIFICATE_VERIFY_FAILED

This is raised by Python's ssl module before any HTTP happens: the TLS handshake succeeded far enough to receive the server's certificate, but your client could not build a trusted chain from it to a root certificate it trusts. The text after the colon tells you why, most often "unable to get local issuer certificate", "self-signed certificate in certificate chain" or "certificate has expired".

Browsers often succeed where scripts fail because browsers use the operating system's trust store and can fetch missing intermediate certificates, while Python uses its own CA bundle (requests uses certifi). On macOS, the python.org installer needs its "Install Certificates" step. On corporate networks, a TLS-inspecting proxy re-signs traffic with a company root that Python does not know.

What is not wrong: the site is not blocking you, and your code logic is fine.

$ pip install --upgrade certifi
$ export REQUESTS_CA_BUNDLE=/etc/ssl/certs/corp-root.pem   # only if a corporate proxy re-signs TLS
$ openssl s_client -connect example.com:443 -servername example.com -showcerts

Pin dependency versions but update certifi regularly, bake the correct CA bundle into container images, and document any corporate root certificate in your environment setup instead of turning verification off.