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].
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...
[2]: https://bitcoin.stackexchange.com/questions/75733/why-does-b...