Thank you for the interesting question! Indeed, the baseline for unpredictability is not strictly defined. I used unpredictability to describe whether an attacker can accurately predict future values. Btfy has parameters such as the difficulty of the VDF and the tolerance range for temperature observation errors. These parameters are related to unpredictability, and we plan to determine appropriate values through future verification and research. I would also love to hear everyone's opinions on how to more appropriately formalize or quantify the baseline for unpredictability!