If @ethereum wants to blend some amount of fast "heartbeat" confirmations with a slower and more resilient trailing finalization protocol, they should learn from and possibly just straight-up use @zcash's world-class work on the Trailing Finality Layer. The constructions are converging, and in my view @zcash has made very clear arguments as to why bounded availability is a better choice to keep users safe which also apply to @ethereum. Full arguments 👇