We study the builder-driven MEV arbitrage on BNB Smart Chain (BSC). BSC's Proposer--Builder Separation (PBS) adopts a leaner design: only whitelisted builders can participate, blocks are produced at shorter intervals, and private order flow bypasses the public mempool. These features have long raised community concerns over centralization, which we empirically confirm by tracing arbitrage activity of the two dominant builders from May to November 2025. Within months, 48Club and Blockrazor produced over 96\% of blocks and captured about 92\% of MEV profits. We find that profits concentrate in short, low-hop arbitrage routes over wrapped tokens and stablecoins, and that block construction rapidly converges toward monopoly. Beyond concentration alone, our analysis reveals a structural source of inequality: BSC's short block interval and whitelisted PBS collapse the contestable window for MEV competition, amplifying latency advantages and excluding slower builders and searchers. MEV extraction on BSC is not only more centralized than on Ethereum, but also structurally more vulnerable to censorship and weakened fairness.

翻译：本研究探讨了BNB智能链（BSC）上由构建者驱动的MEV套利机制。BSC采用的提议者-构建者分离（PBS）方案采用更精简的设计：仅允许白名单构建者参与，区块生成间隔更短，且私有订单流绕过公共内存池。这些特性长期引发社区对中心化的担忧，我们通过追踪2025年5月至11月期间两大主导构建者的套利活动，对此进行了实证验证。在数月内，48Club与Blockrazor生产了超过96%的区块，并攫取了约92%的MEV收益。研究发现，收益集中于封装代币与稳定币的短路径、低跳数套利路线，且区块构建迅速趋向垄断。除集中化现象外，分析进一步揭示了不平等性的结构性根源：BSC的短区块间隔与白名单PBS机制大幅压缩了MEV竞争的可争夺窗口期，放大了延迟优势，导致低速构建者与搜索者被排除在外。BSC上的MEV提取不仅比以太坊更为中心化，其结构也更容易受到审查干扰，并削弱了公平性。