The discussion centers around whether the term "extra pool sizes" refers to the additional transactions held for compact block reconstruction or if it pertains to variations in mempool sizes among peers. The significance of tracking a peer's feefilter is highlighted as a strategy for estimating their pool size, despite inherent limitations in accuracy due to the method of calculation and privacy considerations. The feefilter's effectiveness is influenced by factors such as its half-life calculation, differences in memory usage by various mempool maps, and intentional rounding designed to preserve user privacy. This exploration sheds light on the complexities of managing blockchain network interactions and the challenges of optimizing transaction processing and block reconstruction efforts.