dtonon on Nostr: The fact that nobody knows the bias doesn't help in any way. Think about an extreme ...

The fact that nobody knows the bias doesn't help in any way.
Think about an extreme situation: a die that lands on the same side 80% of the time because that side has specific dimensions or weight. You're killing the entropy, of course, and the derived key is weak against bruteforcing.
The dice in the photo could easily have a similar important bias that impact the entropy, and that bias is certainly more compared to a casual, not intentionally altered, dice that you can bought around.