Does the PoA Model Fully Eliminate the ‘Nothing-at-Stake’ Problem?

PoA significantly mitigates the 'nothing-at-stake' problem but may not fully eliminate it. The initial PoW phase ensures a real-world cost for creating the block template, which is the primary deterrent.

However, the subsequent PoS validation phase still involves stakers signing the block. While the combination is stronger, a sophisticated attack involving coordinated PoW mining and PoS signing could still pose a risk, though it is highly impractical.