According to BitMEX Research, OP_Return2 is a proposed Bitcoin (BTC) transaction output that commits a hash to up to 8MB of arbitrary data while nodes are not required to have that data to validate blocks, so miners and full nodes do not need to validate, relay, or store the extra data (source: BitMEX Research on X, Oct 9, 2025). OP_Return2 would be implemented via a softfork that changes the block weight formula to 8 times base data plus 2 times witness data plus claimed OP_Return2 data store being less than 8 million units (source: BitMEX Research on X, Oct 9, 2025). Special full data archive nodes could optionally relay and store the extra arbitrary data if available, while consensus rules would only require specifying the amount of extra data, and a fee to miners would be paid based on the specified data amount (source: BitMEX Research on X, Oct 9, 2025). Potential disadvantages highlighted include unclear willingness to pay for extra data when miners and nodes are not storing it, limited added value compared with OpenTimestamps with higher per-byte cost, and questions over whether a softfork is necessary given existing hash-in-chain plus external storage approaches (source: BitMEX Research on X, Oct 9, 2025). BitMEX Research also cautions that extra spam data could outbid legitimate payment transactions due to a steeper fee discount per byte, with an 8MB per-block size limit enabling 8MB of spam images to compete at the same cost as a 4MB Taproot witness inscription (source: BitMEX Research on X, Oct 9, 2025).

According to @Excellion, OP_RETURN2 is a potential Bitcoin soft-fork concept proposing a cheaper, fully discardable OP_RETURN2 annex not included in transaction hashes, limiting OP_RETURN via consensus rules, and removing the SegWit discount. Source: https://x.com/Excellion/status/1974608749429137533 Removing the SegWit discount would increase the effective weight of witness data toward 4 weight units per byte (like base data) from the discounted 1 weight unit, directly raising fees for witness-heavy transactions per the BIP-141 weight formula. Source: https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki Ordinals inscriptions embed content in Taproot witness data, so higher witness costs would directly raise on-chain inscription costs and could reduce activity in inscription-heavy markets such as BRC-20. Source: https://docs.ordinals.com/inscriptions.html Soft-fork proposals are typically discussed on the bitcoin-dev mailing list and formalized as BIPs, creating public milestones traders can monitor for potential timing and market impact on BTC fees and throughput. Source: https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev