Hey @quantoid,
When the team was designing st.session_state they had played around with a few options on how state would interact with parameters like value for specifying default ones. For right now, this is expected behaviour but the team is looking into changing it, along with some other changes they are considering for state.
We will circle back to this in the near future. In the meantime, you can remove the value parameter and that will remove the warning your seeing.
Hope this helps!
Happy Streamlit-ing!
Marisa