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Sequencer Bottleneck

Definition

A Sequencer Bottleneck describes a point of congestion or centralization in the process of ordering and submitting transactions to a Layer 1 blockchain from a Layer 2 rollup. In many optimistic and ZK-rollups, a single sequencer currently holds the responsibility for batching transactions, executing them, and posting the data to the main chain. This centralized role, while efficient, introduces potential risks such as censorship, single points of failure, and opportunities for Maximal Extractable Value (MEV) exploitation. It limits the overall decentralization of the Layer 2 solution.