For Cloudflare users:
Security Rules:

(http.request.uri.path eq "/api/v3/comment/list" and not http.request.uri.query contains "post_id")

For Caddy users:

  # >>> Specific handler for /api/v3/comment/list with post_id check
  handle_path /api/v3/comment/list {
    # Check if the 'post_id' query parameter is present
    @hasPostId {
      query post_id=*
    }
    # Abort the connection if the parameter is missing
    handle @hasPostId {
      reverse_proxy http://localhost:8536/
    }
    # This handles all requests that did not match @hasPostId
    abort
  }