Cloudflare has implemented a hybrid encryption scheme combining X25519 and ML-KEM for TLS security to address potential HNDL (Harvest Now, Decrypt Later) attacks. This approach aims to leverage the security of both a post-quantum scheme (ML-KEM) and a classical one (X25519). Apple and Signal have adopted similar hybrid post-quantum encryption protocols, but the deployment of post-quantum digital signatures is delayed due to performance concerns until a quantum computer capable of breaking current systems is on the horizon. Most public blockchains, such as Bitcoin and Ethereum, primarily use digital signatures for transaction authorization rather than encryption, which makes them less vulnerable to HNDL attacks. The real risk lies in signature forgery, where attackers derive private keys to steal funds. Misunderstandings persist, even from credible sources like the Federal Reserve, regarding Bitcoin's vulnerability to HNDL attacks, which may create unnecessary urgency for transitioning to post-quantum cryptography. Privacy-focused blockchains, on the other hand, encrypt transaction details, making them susceptible to retroactive deanonymization if a quantum computer breaks their underlying encryption. For privacy chains, the risk level varies based on design. Monero's ring signatures present a higher risk of reconstructing transaction graphs than other systems. Users of privacy chains should consider transitioning to post-quantum cryptography or adopting designs that limit on-chain decryptable secrets. Bitcoin faces unique challenges in adopting post-quantum signatures due to governance issues and the need for active migration of coins. Many potentially vulnerable coins may be abandoned, leaving them exposed to quantum attacks. Once quantum computers can crack keys, attackers will likely target high-value wallets first, complicating the situation for users relying on outdated practices like address reuse.