Bitcoin Core v30 sparks row over OP_RETURN expansion

Bitcoin Core 30.0 is out, and it’s already divisive. The release introduces optional encrypted connections between nodes for better privacy and relaxes long‑standing limits on OP_RETURN that let transactions carry arbitrary data.

One headline change is more room for "notes" in transactions. Bitcoin Core raises the default data‑carrier allowance from tiny 80 bytes to roughly 100 KB and permits multiple OP_RETURN fields. This is a software policy, not a rewrite of Bitcoin’s rules: miners and node operators can keep stricter limits, so the real‑world effect depends on what settings the network adopts.

Critics call it a step toward blockchain bloat. Security researcher Ox HaK argued that lifting the cap invites “junk data, inscriptions and fee spikes” that punish regular users. Nick Szabo urged operators to hold off on upgrading and, as a temporary measure, run Luke Dashjr’s Knots client to keep strict data limits – an option a meaningful share of nodes already use. Legal concerns surfaced too: archival nodes might end up hosting illicit content without practical tools to remove it.

Fee policy defaults also loosen a bit, so nodes could accept cheaper transactions in theory. That doesn’t guarantee confirmations: unless most of the network embraces the new levels, ultra‑low‑fee transactions may still stall. Developers also added a safety cap on certain old‑style signatures per transaction – housekeeping to prevent abuse and to pave the way for future upgrades.