Zcash developers have targeted January 2027 for introducing post-quantum signature opcodes to protect transparent transactions.

From the articleZcash Developer Zakura Proposes Fix to Stop Quantum Computers Linking Shielded Swaps - DecryptAlso in Zcash developer proposes quantum privacy fix for NEAR Intents swaps, Zakura Proposes One-Time Viewing Keys to Stop Quantum Linking of Zcash Swaps, Zcash developers plan a fix to keep ZEC swaps private from future quantum computers