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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{
    size_t max_extra_txn = gArgs.GetArg("-blockreconstructionextratxn", DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN);
    if (max_extra_txn <= 0)
        return;
    if (!vExtraTxnForCompact.size())
        vExtraTxnForCompact.resize(max_extra_txn);
    vExtraTxnForCompact[vExtraTxnForCompactIt] = std::make_pair(tx->GetWitnessHash(), tx);
    vExtraTxnForCompactIt = (vExtraTxnForCompactIt + 1) % max_extra_txn;
}
void PeerManagerImpl::Misbehaving(const NodeId pnode, const int howmuch, const std::string& message)
{
    assert(howmuch > 0);
    PeerRef peer = GetPeerRef(pnode);
    if (peer == nullptr) return;
    LOCK(peer->m_misbehavior_mutex);
    peer->m_misbehavior_score += howmuch;
    const std::string message_prefixed = message.empty() ? "" : (": " + message);
    if (peer->m_misbehavior_score >= DISCOURAGEMENT_THRESHOLD && peer->m_misbehavior_score - howmuch < DISCOURAGEMENT_THRESHOLD) {
        LogPrint(BCLog::NET, "Misbehaving: peer=%d (%d -> %d) DISCOURAGE THRESHOLD EXCEEDED%s\n", pnode, peer->m_misbehavior_score - howmuch, peer->m_misbehavior_score, message_prefixed);
        peer->m_should_discourage = true;
    } else {
        LogPrint(BCLog::NET, "Misbehaving: peer=%d (%d -> %d)%s\n", pnode, peer->m_misbehavior_score - howmuch, peer->m_misbehavior_score, message_prefixed);
    }
}
bool PeerManagerImpl::MaybePunishNodeForBlock(NodeId nodeid, const BlockValidationState& state,