According to a report by CoinMeta, DEX aggregation protocol 0x has revealed systemic price fraud by some propAMMs on the Base network. The research found that these operators exploit Base's Flashblock architecture, posting highly attractive prices in the final 200 milliseconds before the end of a block (the last Flashblock) to entice aggregators to route their services, only to immediately adjust the price at the start of the next block. This behavior typically results in traders facing an additional loss of 5 to 10 basis points. Based on a monthly trading volume of $1 billion, a single liquidity source could potentially lead to users losing an extra $500,000 per month. Furthermore, the report also points out that some operators maliciously widen spreads by exploiting the delay between price and settlement, or manipulate LP rewards through "phantom liquidity"—depositing large amounts of liquidity before the end of a block and quickly withdrawing it at the start of the next block. This causes aggregators to guide users onto paths with higher slippage due to incorrect depth data. 0x stated that it currently integrates 5 propAMMs on the Base network but will protect users by continuously monitoring execution quality and cutting off sources of fraudulent liquidity.