How Does a 2/3 Majority PoS Signature Threshold Affect PoA Finality?

A 2/3 majority signature threshold in the PoS phase of PoA provides a high degree of finality. Once 2/3 of the total staked coins (or the validators representing them) have signed the block, the block is considered finalized and immutable under the protocol's rules.

This cryptographic commitment makes chain reorgs extremely difficult, as it would require 2/3 of the stake to collude and risk being slashed.