OpenAPI encoding refs for non-URI-safe strings

Question

When referencing other other elements in an OpenAPI document, how does one encode non-URI-safe strings?

An example of what I mean

Here I have a response in one operation (default in /path/one), and I'm trying to reference this response from another operation (default in /path/two). To get the URI fragment to given response, I need to include a key (/path/one) which has URI-forbidden characters (/):

openapi: 3.0.0
paths:
  /path/one:
    get:
      responses:
        default:
          description: A normal response
          content:
            application/json:
              schema:
                type: string
  /path/two:
    get:
      responses:
        default:
          # This is the important part
          $ref: "#/paths/%2path%2one/get/responses/default"

As demonstrated above, I'd do this by simply URL-encoding the problematic parts.

The reason I'm asking this question, is because on https://apis.guru I found an OpenAPI document (this one: https://api.apis.guru/v2/specs/brex.io/2021.12/openapi.yaml) where they are using the ~ character to "encode" the / character.

Is this standard or is this a one-of issue with said OpenAPI document?