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 (m_connman.GetExtraBlockRelayCount() > 0) {
        std::pair<NodeId, int64_t> youngest_peer{-1, 0}, next_youngest_peer{-1, 0};
        m_connman.ForEachNode([&](CNode* pnode) {
            if (!pnode->IsBlockOnlyConn() || pnode->fDisconnect) return;
            if (pnode->GetId() > youngest_peer.first) {
                next_youngest_peer = youngest_peer;
                youngest_peer.first = pnode->GetId();
                youngest_peer.second = pnode->nLastBlockTime;
            }
        });
        NodeId to_disconnect = youngest_peer.first;
        if (youngest_peer.second > next_youngest_peer.second) {
            
            
            to_disconnect = next_youngest_peer.first;
        }
        m_connman.ForNode(to_disconnect, [&](CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
            AssertLockHeld(::cs_main);
            
            
            
            
            
            CNodeState *node_state = State(pnode->GetId());
            if (node_state == nullptr ||
                (time_in_seconds - pnode->nTimeConnected >= MINIMUM_CONNECT_TIME && node_state->nBlocksInFlight == 0)) {
                pnode->fDisconnect = true;
                LogPrint(BCLog::NET, "disconnecting extra block-relay-only peer=%d (last block received at time %d)\n", pnode->GetId(), pnode->nLastBlockTime);