I want to admit that I am pretty new to elixir but after digging a little bit I managed to get it to work using this:

Plug Repository

  # covers non-keyword lists
  defp encode_pair(parent_field, list, encoder) when is_list(list) do
    mapper = fn
      value when is_map(value) and map_size(value) != 1 ->
        raise ArgumentError,
              "cannot encode maps inside lists when the map has 0 or more than 1 element, " <>
                "got: #{inspect(value)}"

      value ->
        [?&, encode_pair(parent_field <> "", value, encoder)]
    end

    list
    |> Enum.flat_map(mapper)
    |> prune()
  end

instead of [?&, encode_pair(parent_field <> "[]", value, encoder)] in last line, i just removed the [] like this: [?&, encode_pair(parent_field <> "", value, encoder)]

what I want to know if this is the right way to do it? and would this cause any issues noting that I am only going to be using it for this API call?