Zakura's design uses private information retrieval to enable wallets to look up refund transactions during restoration without exposing queried addresses to database operators.

From the articleZcash developers plan a fix to keep ZEC swaps private from future quantum computersAlso in Zakura Proposes One-Time Viewing Keys to Stop Quantum Linking of Zcash Swaps, Zcash Builder Zakura Proposes Per-Swap Viewing Keys to Close a Quantum Privacy Gap - Unchained, Zcash Developer Zakura Proposes Fix to Stop Quantum Computers Linking Shielded Swaps - Decrypt, Zcash Proposes New Privacy Layer to Guard Swaps From Quantum Risks, Zcash developer proposes quantum privacy fix for NEAR Intents swaps, ZEC tops $1,171 as quantum-proofing work speeds up - Inside Zakura's proposal - AMBCrypto