How can I determine the specific TLS version npm is attempting to use?

You can use a network debugging tool like Wireshark or tcpdump to capture the network traffic between your Node.js application and the npm registry. Analyzing the captured data will show you the TLS version negotiated during the handshake. Alternatively, you can use a tool like `openssl s_client -connect registry.npmjs.org:443 -tls1_2` (replace `tls1_2` with other TLS versions to test) to test the TLS connection directly and see which versions are supported.