According to Woofun AI, the Zcash network is about to implement a NU7 upgrade, causing its oldest Sprout privacy pool to risk being permanently frozen, involving assets worth around $16 million. This upgrade will reject the version 4 transaction format, making it impossible for holders to use the pool's cryptocurrencies even if they have private keys. This is a critical watershed in the evolution of Zcash's privacy protocol.
Since launching with the Zcash network in October 2016, the Sprout pool has been replaced by more advanced privacy technology. According to data compiled by Woofun AI, as of Thursday morning, the number of ZEC left in the pool was about 12,226, a significant decrease from 22,263 a week ago. Of these, 9,094 were released in a single day on Sunday, and another 40 were withdrawn on Wednesday. The current block height is 3,542,391, and there are only about 1,014 blocks left from the upgrade block 3,543,405. Based on blocks generated every 75 seconds, the remaining time is about 21 hours. The freeze is expected to take effect around 9:30 p.m. EST on Thursday. Although these address assets starting with “zc” are still included in the total amount of Zcash issued, the ZIP 2003 standard indicates that they may never be used again, and keeping them running increases the complexity and security risks of verifying software.
The core of the NU7 upgrade is to improve network efficiency and security. In addition to freezing the Sprout pool, the upgrade also reduced the block generation interval from 75 seconds to 25 seconds, significantly reducing the wait time for transaction confirmation. Since the public fund pool cannot identify the holder and determine the exact amount of money in the wallet where the private key was lost, the final scale of the freeze depends on last-minute withdrawals. Based on $1,300 per ZEC, the total value of the current remaining currency is approximately $16 million. If withdrawals are made in the future, this figure will drop further.
This upgrade marks Zcash's complete departure from earlier privacy protocols and a shift to a more efficient and secure architecture. As the Sprout pool shuts down, network complexity is reduced and security is improved, but it also means that some early users may lose access to assets forever. This is another major trade-off between decentralization and user experience by Zcash after many iterations of the privacy protocol. Future improvements in network performance will depend on the actual operation of the new protocol.