How Does the “Nothing at Stake” Problem, Often Associated with PoS, Relate to PoA?

The "nothing at stake" problem occurs in pure PoS when validators can vote on multiple chain histories at no cost, leading to potential chain instability. PoA mitigates this because the initial block creation requires PoW effort.

This initial cost makes it economically punitive to create multiple competing chains, as the miner would waste significant energy. The PoW phase acts as a check on malicious behavior.