Quantum computing attacks may already be occurring. The advent of a quantum machine capable of cracking RSA encryption (and similar public-key encryption methods) is years away. However, the threat of retroactive decryption exists today. Retroactive decryption (aka “harvest and decrypt”) involves bad actors stealing encrypted data and communications by tapping fiber-optic networks. They store this data with the intent to decrypt it once universal quantum computers (or cloud access to them) become widely available. Large US banks are investing early and heavily in quantum key distribution to protect sensitive data from “hack now, decrypt later” attacks.

https://novarica.com/2020/06/thoughts-from-inside-quantum-technology-2020/