The developers of Bitcoin Core, the primary open-source software for connecting the blockchain behind the world's largest cryptocurrency, said October's version 30 release will increase the default limit for OP_RETURN data transactions from the current 80 bytes to nearly 4MB, a limit imposed by Bitcoin's block size.The proposal for the change, which was confirmed in an update on GitHub, had sparked debate within the Bitcoin community. Critics argued that removing the limit could encourage increased embedding of arbitrary data, potentially leading to network spam and a shift from bitcoin's BTC primary function as a financial tool.This decision to go ahead marks another significant moment in the community's debate about blockchain usage, highlighting persistent tensions between network efficiency, practical use cases and ideological principles
source: https://www.coindesk.com/tech/2025/06/10/bitcoin-core-30-to-increase-op_return-data-limit-after-developer-debate-concludes