There are some potential feefilter cleanups mentioned and motivated in comment https://github.com/bitcoin/bitcoin/pull/21509#issuecomment-805808485 . If you address the locking one, please be careful and make sure that `round()` is only called under a lock. See https://github.com/bitcoin/bitcoin/pull/21509#issuecomment-807992199

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if (state.GetResult() == TxValidationResult::TX_INPUTS_NOT_STANDARD && tx.GetWitnessHash() != tx.GetHash()) {
                    recentRejects->insert(tx.GetHash());
                    m_txrequest.ForgetTxHash(tx.GetHash());
                }
                if (RecursiveDynamicUsage(*ptx) < 100000) {
                    AddToCompactExtraTransactions(ptx);
                }
            }
        }
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        if (state.IsInvalid()) {
            LogPrint(BCLog::MEMPOOLREJ, "%s from peer=%d was not accepted: %s\n", tx.GetHash().ToString(),
                pfrom.GetId(),
                state.ToString());
            MaybePunishNodeForTx(pfrom.GetId(), state);