oh-my-posh/docs/api/proxies.json

{
  "$schema": "http://json.schemastore.org/proxies",
  "proxies": {
    "callback": {
      "debug": true,
      "matchCondition": {
        "methods": ["GET", "POST"],
        "route": "/api/auth"
      },
      "backendUri": "%API_LOCATION%/api/auth",
      "requestOverrides": {
        "backend.request.querystring.code": "",
        "backend.request.querystring._code": "{request.querystring.code}"
      }
    }
  }
}