Monad's post-quantum Cadence deconstruction: why is its technical path diametrically opposed to Ethereum's?

Monad developer Category Labs on October 27 unveiled Quantum Cadence, a post-quantum upgrade to its multi-proposer Cadence consensus that strips aggregated signature bundles from the consensus critical path entirely, rather than replacing them as Ethereum plans to do with leanXMSS signatures and SNARK compression across its roughly 860,000 active validators on 12-second slots. In simulations with 200 validators on 1Gbps links, 100 parallel proposers and 5,000-byte signatures, Quantum Cadence cut per-validator upload bandwidth 27% to 561Mbps from 772Mbps while reaching finality in 231 milliseconds versus 229 milliseconds for the original protocol, with heavy post-quantum signatures reserved only for after-the-fact slashing. The design matters because Monad's 100-millisecond slot target cannot absorb SNARK aggregation latency, forcing it to rely on authenticated communication channels and local vote counting instead of quorum certificates. Cadence itself has not yet launched on mainnet, so Quantum Cadence is a strategic reserve; watch for a mainnet timeline and whether other high-throughput chains adopt the no-certificate approach as quantum threats are expected in the early-to-mid 2030s.