adding @@@@ (AT symbols) to my url sometimes works as expected and sometimes does not

Question

We have a lambda function that has been set up to verify that what we're passing in the url is a valid CUID.

@@@@ is not a valid CUID and we have set it up to respond as a 400 with the error message stating that is is not a valid CUID. This works most the time.

I am using combination superagent, cucumber-tsflow and chai to send http requests and assert the response.

Occasionally i get issues with @@@@ in our url.

Example url: https://ourcompany.com/v1/id/@@@@/accounts'

In cucumber i am occasionally seeing the following:

.Request {
  _events: [Object: null prototype] {
    end: [Function: bound onceWrapper] { listener: [Function: bound ] }
  },
  _eventsCount: 1,
  _maxListeners: undefined,
  _enableHttp2: false,
  _agent: false,
  _formData: null,
  method: 'GET',
  url: 'https://ourcompany.com/v1/id/@@@@/accounts',
  _header: {},
  header: {},
  writable: true,
  _redirects: 0,
  _maxRedirects: 5,
  cookies: '',
  qs: {},
  _query: [],
  qsRaw: [],
  _redirectList: [],
  _streamRequest: false,
  [Symbol(kCapture)]: false
}

And the error from the attempt to send the request.

Then I will receive a 400 HTTP response # node_modules\cucumber-tsflow\src\binding-decorator.ts:216
       TypeError: Cannot read properties of undefined (reading 'statusCode')

I am making the assumption that the request has failed to send. I do not see it hitting our lambda in the logs. Is there any reason why using @@@@ inside the url might sometimes cause issues for superagent library but not all the time?

I have similar tests where I use !@!@! instead og @@@@ and it never has issues.