Here is what the page “Zcash NU7 Upgrade Goes Live, Stranding 12,224 ZEC in Legacy Sprout Pool” contains. The Zcash network's NU7 upgrade is now live, and with it, roughly 12,224 ZEC—worth about $15 million at current prices—in the legacy Sprout shielded pool has become unspendable. The upgrade, which introduces new consensus rules and cryptographic improvements, effectively cuts off access to funds tha The upgrade, which introduces new consensus rules and cryptographic improvements, effectively cuts off access to funds that have remained in the original Sprout pool since Zcash's early days.
Users who had not migrated their Sprout funds to the newer Sapling or Orchard pools before the activation can no longer move them. This affects a small but notable portion of the total ZEC supply, and the stranded coins are now frozen indefinitely. The Zcash community and developers have acknowledged the situation, noting that a future network upgrade could potentially restore access if a consensus change is approved. For the complete material, the listing points back to the source inside the network.