Flashbots' new report points out that the junk transactions generated by Maximal Extractable Value (MEV) bots are occupying block space faster than blockchain networks can scale, becoming the main bottleneck for blockchain scalability. MEV refers to the maximum profit validators can obtain by reordering, inserting, or excluding transactions within a block. The study found that MEV bots consume over 50% of the gas on leading OP-Stack rollups but pay less than 10% of the fees, causing increased transaction costs for ordinary users. Especially on Coinbase's Base network, two bots account for over 80% of the junk transactions. The report also notes that on Solana, MEV bots occupy about 40% of block space, indicating that economic congestion, rather than technical bandwidth, limits actual scalability. Flashbots believe the current "junk auction" market structure incentivizes bots to send a large number of speculative arbitrage transactions. While technical upgrades like database sharding help, they are insufficient to solve the problem. To address this, Flashbots proposes replacing gas-based bidding with a two-part design that grants searchers programmable privacy and allows them to submit off-chain bids in dedicated auctions, using Trusted Execution Environments (TEEs) to prevent front-running and return value to validators and users. If adopted, this solution is expected to free up most congestion capacity, reduce fees, and create space for new applications.

Maximal extractable value, or MEV, has “become the dominant limit to scaling blockchains,” research group Flashbots warned in a new report released Monday. The paper argues that spam transactions generated by MEV bots are soaking up blockspace faster than networks can add it, nullifying recent breakthroughs in raw throughput.MEV is the maximum profit that validators can earn by reordering, inserting, or excluding transactions in a block before it is finalized.Flashbots found that spam bots routinely consume more than 50% of gas on leading OP-Stack rollups while paying under 10 % of total fees, pushing baseline transaction costs higher for everyday users. “Bots often send hundreds of transactions for a single low-margin arbitrage. While profitable for the bots, it’s wasteful for the network, burdening nodes and users,” the group wrote.The issue is particularly concentrated on networks like Coinbase’s Base network, where two bots account for over 80 % of spam transactions, the study said.“Between November 2024 and February 2025, Base added 11M in gas/s throughput, and almost all of it was consumed by spam bots,” Flashbots wrote. That equates to three Ethereum Mainnets worth of capacity, according to the report.The problem also extends beyond Ethereum’s Layer 2 ecosystem. On Solana, MEV bots now occupy about 40 % of blockspace, the researchers added. The group said the data indicates how economic congestion, not technical bandwidth, is capping real-world scalability.Indeed, Flashbots blames today’s “spam auction” market structure, where bots flood blocks with speculative arbitrage transactions because private mempools hide pending order flow. While technical upgrades like database sharding stem the problem, they are ineffective alone, the report said.To address the MEV-driven bottleneck, Flashbots proposed replacing gas-based bidding with a two-part design. The potential fix would grant searchers, or MEV bots operators, programmable privacy and allow them to submit explicit, off-chain bids for transaction ordering in a dedicated auction. Trusted-execution environments would reveal user flows without allowing frontrunning, while the auction channels value back to validators and users.If adopted, Flashbots argues that the overhaul could free up most of today’s congested capacity, lower fees, and restore headroom for new applications.

Flashbots Report: MEV Bot Spam Transactions Become Major Bottleneck for Blockchain Scaling