proxy-authentication header missing with https - node.js

Question

I want to create a mitm proxy that can only be access by providing correct credentials:
(async () => {
const mockttp = require('mockttp');
// Create a proxy server with a self-signed HTTPS CA certificate:
const https = await mockttp.generateCACertificate();
const server = mockttp.getLocal({ https });
// Inject 'Hello world' responses for all requests
// Replace targets entirely with custom logic:
let counter = 0;
server.forAnyRequest().thenCallback((request) => {
console.log(JSON.stringify(request));
return {
status: 200,
// Return a JSON response with an incrementing counter:
json: { counterValue: counter++ }
};
});
await server.start(8080);
// Print out the server details:
const caFingerprint = mockttp.generateSPKIFingerprint(https.cert)
console.log(`Server running on port ${server.port}`);
console.log(`CA cert fingerprint ${caFingerprint}`);
})(); // (Run in an async wrapper so we can use top-level await everywhere)
With http it works flawlessly, the proxy-authorization header is present:
curl -k -v --proxy "user:pass#127.0.0.1:8080" http://www.google.com
{
"id":"8978f1a3-8a4f-4395-b0dc-0cf8929e760a",
"matchedRuleId":"5a1bc167-7e34-4b0d-9f51-f8e49015b349",
"protocol":"http",
"httpVersion":"1.1",
"method":"GET",
"url":"http://www.google.com/",
"path":"/",
"remoteIpAddress":"::ffff:127.0.0.1",
"remotePort":32932,
"headers":{
"host":"www.google.com",
"proxy-authorization":"Basic dXNlcjpwYXNz",
"user-agent":"curl/7.83.1",
"accept":"*/*",
"proxy-connection":"Keep-Alive"
},
"rawHeaders":[
[
"Host",
"www.google.com"
],
[
"Proxy-Authorization",
"Basic dXNlcjpwYXNz"
],
[
"User-Agent",
"curl/7.83.1"
],
[
"Accept",
"*/*"
],
[
"Proxy-Connection",
"Keep-Alive"
]
],
"tags":[
],
"timingEvents":{
"startTime":1663860475270,
"startTimestamp":7655.8840999901295,
"bodyReceivedTimestamp":7656.588100001216
},
"body":{
"buffer":{
"type":"Buffer",
"data":[
]
}
}
}
Now the problem is that if it runs through https, the proxy-authorization disappears:
curl -k -v --proxy "user:pass#127.0.0.1:8080" https://www.google.com
{
"id":"dd9f61c9-8ecb-4f94-87aa-095fd2f40da6",
"matchedRuleId":"5a1bc167-7e34-4b0d-9f51-f8e49015b349",
"protocol":"https",
"httpVersion":"1.1",
"method":"GET",
"url":"https://www.google.com/",
"path":"/",
"remoteIpAddress":"::ffff:127.0.0.1",
"remotePort":34557,
"headers":{
"host":"www.google.com",
"user-agent":"curl/7.83.1",
"accept":"*/*"
},
"rawHeaders":[
[
"Host",
"www.google.com"
],
[
"User-Agent",
"curl/7.83.1"
],
[
"Accept",
"*/*"
]
],
"tags":[
],
"timingEvents":{
"startTime":1663860737403,
"startTimestamp":269786.7910999954,
"bodyReceivedTimestamp":269787.29159998894
},
"body":{
"buffer":{
"type":"Buffer",
"data":[
]
}
}
}
Is there anything I'm unaware of that causes this behaviour?