A significant bug in Zcash's code, undetected for four years, has been discovered by AI, leading to its exclusion from decentralized finance (DeFi) applications. The vulnerability, which could have been exploited to compromise user privacy, was identified by an AI tool designed to enhance blockchain security. As a result, Zcash is now deemed unsuitable for integration with DeFi platforms until further notice, highlighting the critical role of AI in maintaining blockchain integrity.