Add amplification aspect to hard-fork as a transition period

Author: ch1bo

docs/threat-model.md

@@ -296,7 +296,7 @@ Backward compatibility failures represent a particularly critical risk, as demon
 
 Excessive chain growth poses a different challenge where the success of Leios could paradoxically threaten decentralization. If transaction throughput increases faster than SPO storage capabilities, honest stake could be forced offline due to resource constraints, inadvertently concentrating power among well-resourced operators and giving adversaries advantages in most stake-based attacks.
 
-**Impact**: These threats can undermine the fundamental assumptions that keep Cardano secure and decentralized. Backward compatibility failures create chain splits that require manual coordination to resolve. Governance attacks can prevent beneficial upgrades entirely or create persistent network splits. Excessive growth can force honest operators offline, reducing effective honest stake and strengthening potential attackers' relative position in all stake-based attacks.
+**Impact**: These threats can undermine the fundamental assumptions that keep Cardano secure and decentralized. Backward compatibility failures create chain splits that require manual coordination to resolve. Governance attacks can prevent beneficial upgrades entirely or create persistent network splits. Excessive growth can force honest operators offline, reducing effective honest stake and strengthening potential attackers' relative position in all stake-based attacks. Importantly, the network is most vulnerable during hard fork transition periods when mixed versions, uncertain governance outcomes, and coordination challenges create opportunities for adversaries to amplify other attack vectors from across the threat landscape.
 
 **Assets Affected**: Blockchain Safety, Blockchain Liveness, Decentralization, Operational Sustainability