It depends on the type of bonus round. For 'pick a bonus' rounds, where you choose symbols to reveal prizes, the outcome is often predetermined. The RNG selects a result from a set range, which is then presented to you as a choice. However, if the game reveals where all possible outcomes were after you pick, then it's not predetermined. On the other hand, free spins rounds are not predetermined and each spin within the bonus is a separate random event, just like regular spins.
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