Bitcoin's Concentrated Mining Pools Spark Rare 2-Block Reorganization Risk

On March 23, Bitcoin experienced a rare two-block reorganization due to dominant mining pools Foundry, AntPool, and ViaBTC controlling about 60% of the network's hash rate. This concentration challenges the reliability of Bitcoin's six-confirmation finality rule, which assumes a more distributed hashpower. The incident calls for reassessment of transaction security assumptions as mining shares fluctuate and economic pressures intensify.