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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* Bitcoin Core P2P design
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{
    switch (state.GetResult()) {
    case TxValidationResult::TX_RESULT_UNSET:
        break;
    
    case TxValidationResult::TX_CONSENSUS:
        Misbehaving(nodeid, 100, message);
        return true;
    
    case TxValidationResult::TX_RECENT_CONSENSUS_CHANGE:
    case TxValidationResult::TX_INPUTS_NOT_STANDARD:
    case TxValidationResult::TX_NOT_STANDARD:
    case TxValidationResult::TX_MISSING_INPUTS:
    case TxValidationResult::TX_PREMATURE_SPEND:
    case TxValidationResult::TX_WITNESS_MUTATED:
    case TxValidationResult::TX_WITNESS_STRIPPED:
    case TxValidationResult::TX_CONFLICT:
    case TxValidationResult::TX_MEMPOOL_POLICY:
        break;
    }
    if (message != "") {
        LogPrint(BCLog::NET, "peer=%d: %s\n", nodeid, message);
    }
    return false;
}
bool PeerManagerImpl::BlockRequestAllowed(const CBlockIndex* pindex)