The scenario depicted involves a transaction graph with transactions A, B, P1, P2, and P3, where re-linearization could affect the feerate calculations for RBF. Specifically, without re-linearizing, the fee bump required for a new transaction B to replace A could be artificially inflated by an unrelated transaction P2 due to the way mempool chunks are calculated.

An example is provided using a mermaid graph representation to illustrate the structure of transactions and their respective feerates. In the first instance, the graph showcases three transactions with varying feerates, leading to a certain distribution of mempool chunks. When considering replacing transaction A with B and assuming B's feerate increases, two different outcomes for mempool chunk feerates are compared: one with re-linearization and one without. Re-linearization results in a more granular feerate distribution, which seems preferable.

Further investigation involved testing how adjustments to the size or feerate of transaction P2 influence the required feerate for transaction B to be accepted, both with and without re-linearization. A table presents the minimum fee bump necessary for various sizes of P2 at a fixed feerate and for different feerates of P2 at a fixed size.

The findings suggest that not re-linearizing can lead to significantly higher fee bumps required for RBF when increasing either the size or the feerate of P2. This indicates that re-linearizing old clusters is beneficial as it avoids higher fee requirements for the replacement transaction that are influenced by unrelated transactions. Therefore, the conclusion drawn is in favor of re-linearization to ensure RBF operates effectively and does not incur unnecessarily high fees due to the presence of unrelated transactions in the mempool.