Ethereum

Toni's conclusion

"Implementing anti-correlation penalties is a great way to counter economies of scale without requiring the protocol to differentiate between individual validators."

As a community, we'll never be able to save Ethereum from immature design, but we can buy time for researchers to harden the protocol.

https://ethresear.ch/t/analysis-on-correlated-attestation-penalties/19244

I have mentioned before how one could correlate large clusters based on correlated missed attestations. It appears they're currently considering a mechanism similar to how gas prices are decided based on missed attestations. In other words, historcally correlated cluster information isn't considered, only last 4 blocks