Developer Jimmy Song called the removal of the OP_Return limit in Bitcoin Core 30 “fiat thinking.” Some nodes have switched to Bitcoin Knots.

Jimmy Song Criticizes Bitcoin Core: Nodes Are Moving En masse to Bitcoin Knots

Developer and Bitcoin advocate Jimmy Song has sharply criticized the Bitcoin Core team’s decision to remove the 80-byte limit for OP_Return, a field for non-monetary data in the blockchain, in the upcoming release of Bitcoin Core 30.

Song said that ignoring the concerns of users and node runners is “fiat thinking” and resembles the tactics of political debates:

“Non-monetary data in Bitcoin is spam. Just because it’s hard to define the limits doesn’t mean they don’t exist.”

The discussion around OP_Return has been going on for half a year and has been dubbed the “OP_Return wars.” Some in the community even draw parallels with the “block size wars” of 2015–2017, which led to the Bitcoin Cash fork.

Historic node outflow in Bitcoin Knots

The most dramatic reaction was the mass switch of noderunners from Bitcoin Core to Bitcoin Knots, which allows for a strict limit on the size of data in blocks.

• In 2024, Knots held about 1% of nodes.
• Today, this share has grown to 20% in nine months, which was an unprecedented jump.

Knots supporters believe that it is the restrictions that keep the cost of running a node (≈$300 on a regular computer) and guarantee the decentralization of the network.

Centralization as the main threat

Bitcoin has generated only 680 GB of data since its launch in 2009, thanks to its simple architecture and strict limits. This allows anyone to maintain the network.

In comparison, high-throughput blockchains with smart contracts generate much larger volumes of data, requiring expensive server hardware costing tens of thousands of dollars.

Such requirements lead to centralization: only wealthy participants or corporations can run nodes, which increases the risk of collusion and manipulation of consensus.

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