Pleroma doesn't generate a unique signing_salt

mix pleroma.instance gen does not generate a unique signing_salt

This is part of the config :pleroma, Pleroma.Web.Endpoint, section:

# Configures the endpoint
config :pleroma, Pleroma.Web.Endpoint,
  url: [host: "localhost"],
  http: [
    dispatch: [
      {:_,
       [
         {"/api/v1/streaming", Elixir.Pleroma.Web.MastodonAPI.WebsocketHandler, []},
         {"/socket/websocket", Phoenix.Endpoint.CowboyWebSocket,
          {nil, {Pleroma.Web.Endpoint, Pleroma.Web.UserSocket, websocket_config}}},
         {:_, Plug.Adapters.Cowboy.Handler, {Pleroma.Web.Endpoint, []}}
       ]}
    ]
  ],
  protocol: "https",
  # reverse_proxies: ["10.0.0.0/8"],
  secret_key_base: "MiquohF2re4Ahiithohdoeph1eishohkeiroich6oew6oich5fi3EiM6aenar2th",
  signing_salt: "CqaoopA2",
  render_errors: [view: Pleroma.Web.ErrorView, accepts: ~w(json)],
  pubsub: [name: Pleroma.PubSub, adapter: Phoenix.PubSub.PG2],
  secure_cookie_flag: true