PQC: Post-Quantum Cryptography. The concern is systems which won't be resistant against quantum cryptographic attacks. The US's NIST has an explainer page, "

PQC: Post-Quantum Cryptography. The concern is systems which won't be resistant against quantum cryptographic attacks. The US's NIST has an explainer page, "Post-Quantum Cryptography PQC": <https://csrc.nist.gov/projects/post-quantum-cryptography https://csrc.nist.gov/projects/post-quantum-cryptography>.