Zcash NU7 upgrade would freeze Sprout pool, locking 22,309 ZEC in oldest privacy pool

Zcash's proposed NU7 upgrade would close the spending route out of its oldest privacy pool, Sprout, leaving approximately 22,309 ZEC unable to move on the upgraded network. The change, outlined in ZIP 2003, proposes rejecting version 4 transactions from NU7 onward, a format required by Sprout transfers but unsupported by versions 5 and 6. While holders retain their private keys, the network would no longer accept version 4 transactions, effectively locking those funds. A final activation height remains undecided, with a target date of Nov. 5 conditional on the Oct. 20 decision. Recovery options exist but require significant effort, including reconstructing historical data and transferring funds to newer pools like Sapling, which involves privacy trade-offs and fees.