Unsupported expression in Elixir.AshPostgres.SqlImplementation query: `datetime_add`

  defmodule OrgSubscription do
  ...
  attribute :activation_date, :utc_datetime do
    public? true
    allow_nil? false
    default &DateTime.utc_now/0
  end
  ...
  calculate :expiration_date,
            :utc_datetime,
            expr(
              datetime_add(
                activation_date,
                subscription_plan.duration_qty,
                subscription_plan.duration_interval
              )
            )
  end

  attribute :duration_interval, :atom do
    allow_nil? false
    public? true
    constraints one_of: [:day, :week, :month, :year]
    default :year
  end

  attribute :duration_qty, :integer do
    allow_nil? false
    public? true
    constraints min: 1, max: 100
    default 1
  end

Unsupported expression in Elixir.AshPostgres.SqlImplementation query:

%{
  extra: %{},
  name: :datetime_add,
  arguments: [
    %{
      attribute: %{
        default: &DateTime.utc_now/0,
        name: :activation_date,
        type: Ash.Type.UtcDatetime,
        constraints: [
          precision: :second,
          cast_dates_as: :start_of_day,
          timezone: :utc
        ],
      },
    },
    %{
      attribute: %{
        default: 1,
        name: :duration_qty,
        type: Ash.Type.Integer,
        source: :duration_qty,
        constraints: [min: 1, max: 100]
      },
    },
    %{
      attribute: %{
        default: :year,
        name: :duration_interval,
        type: Ash.Type.Atom,
        description: nil,
        source: :duration_interval,
        constraints: [
          one_of: [:day, :week, :month, :year],
          unsafe_to_atom?: false
        ],
      },
    }
  ],
}