What Is a ‘Re-Org’ and How Does It Affect Finality?

A 're-org' (re-organization) occurs when the network temporarily adopts a shorter, alternative chain over the currently accepted longer chain, causing a reversal of transactions in the orphaned blocks. This directly breaks finality for the reversed transactions.

Re-orgs are more common in PoW networks but can happen in PoS if a malicious actor successfully causes a fork. They are a significant risk to immediate settlement.