How Does the Concept of “Immutability” Relate to a Successful 51% Attack?

Immutability refers to the idea that the transaction history on a blockchain, once recorded, cannot be changed. A successful 51% attack temporarily compromises this immutability by forcing a chain reorganization, effectively rewriting a portion of the recent transaction history to reverse a double-spend.

While the core protocol remains immutable, the specific transaction history is proven to be mutable under attack conditions.