Proof of stake selects validators to propose and attest blocks based on staked collateral.
Misbehavior can be punished by slashing stake. Ethereum moved to PoS in the Merge.
In research workflows, Proof of stake is usually interpreted with Ethereum, Validator, Staking, and Liquid staking rather than as a standalone signal. Throughput, finality, and fee markets determine user experience and where activity migrates during congestion.