To be clear, I'm not claiming that any particular implementation of PoS is vulnerable to this exact attack. It's an illustrative example of one class of attack

To be clear, I'm not claiming that any particular implementation of PoS is vulnerable to this exact attack. It's an illustrative example of one class of attack that is a danger on PoS chains but not PoW chains, and might help people intuit why PoS implementations are more complex. Coming back down to earth, this is why ETH requires checkpoints[1], but PoW chains do not[2]. [1]: https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/#finality https://ethereum.org/en/developers/docs/consensus-mechanisms... [2]: https://bitcoin.stackexchange.com/questions/75733/why-does-bitcoin-no-longer-have-checkpoints https://bitcoin.stackexchange.com/questions/75733/why-does-b...