Nested Form with map

I don’t have a Ecto schema for this, so not sure if embeds apply. I am trying to use the input_for and so far have not been able to get very far. Latest error I get is:

* (ArgumentError) the Access calls for keywords expect the key to be an atom, got: "_persistent_id"
    (elixir 1.14.3) lib/access.ex:313: Access.get/3
    (phoenix_live_view 0.20.0) lib/phoenix_component.ex:2415: anonymous fn/2 in Phoenix.Component."inputs_for (overridable 1)"/1
    (elixir 1.14.3) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (phoenix_live_view 0.20.0) lib/phoenix_component.ex:2415: Phoenix.Component."inputs_for (overridable 1)"/1
    (phoenix_live_view 0.20.0) lib/phoenix_live_view/tag_engine.ex:68: Phoenix.LiveView.TagEngine.component/3