Installing npm packages using yarn throws 501 Not Implemented

[Wolfeg]

Describe the bug
Installing packages with npm proxy repository using yarn not working.

To Reproduce

• Create .npmrc with creds to npm proxy
• Install packages with yarn install

Expected behavior
Packages installed

Error text

yarn install v1.22.22
info No lockfile found.
[1/5] Validating package.json...
[2/5] Resolving packages...
info There appears to be trouble with the npm registry (returned undefined). Retrying...
info There appears to be trouble with the npm registry (returned undefined). Retrying...
info There appears to be trouble with the npm registry (returned undefined). Retrying...
info There appears to be trouble with the npm registry (returned undefined). Retrying...
⠂ @babel/code-frame@^7.29.0/usr/lib/node_modules/yarn/lib/util/request-manager.js:431
            throw new (_errors || _load_errors()).ResponseError(this.reporter.lang('requestFailed', description), res.statusCode);
            ^

ResponseError: Request failed "501 Not Implemented"
    at params.callback [as _callback] (/usr/lib/node_modules/yarn/lib/util/request-manager.js:431:19)
    at self.callback (/usr/lib/node_modules/yarn/node_modules/request/request.js:185:22)
    at Request.emit (node:events:519:28)
    at Request.<anonymous> (/usr/lib/node_modules/yarn/node_modules/request/request.js:1157:10)
    at Request.emit (node:events:519:28)
    at IncomingMessage.<anonymous> (/usr/lib/node_modules/yarn/node_modules/request/request.js:1079:12)
    at Object.onceWrapper (node:events:633:28)
    at IncomingMessage.emit (node:events:531:35)
    at endReadableNT (node:internal/streams/readable:1698:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:89:21) {
  responseCode: 501
}

Node.js v22.23.2