How Is the ‘Nothing-at-Stake’ Problem Addressed in Modern PoS Protocols?

The 'nothing-at-stake' problem arises because in a simple PoS system, validators have no cost to vote on multiple competing chain histories after a fork, which prevents the network from converging on a single canonical chain. Modern PoS protocols address this through slashing, where validators who vote for conflicting blocks are penalized.

This economic penalty forces validators to commit to a single chain, solving the issue.