AFAICT, as of commit a0a422c,  we have 2 different logics to evict outbound peers : lagging-chain (`ConsiderEviction`) and (`CheckForStaleTipAndEvictPeers`). The former to sanitize out lazy/buggy peers who have never sent us a valid header and are always staying behind our tip, the latter triggered in case of stale tip due to block variance to seek a better chain by rotating our outbound peers if we already reach an outbound limit (`EvictExtraOutboundPeers`).

Block-relay-only peers were introduced by #15719. Contrary to outbound full-relay peers who provided us at least a useful header, they're not protected by lagging-chain eviction.

We actually have a comment inside `ProcessHeadersMessage` indicating the contrary behavior. We should either document cleanly that block-relay-only aren't protected or effectively extend the scope of protection to them.

Hinted during #19724 review, see https://github.com/bitcoin/bitcoin/pull/19724#discussion_r475144532
LogPrintf("Warning: disconnecting but not discouraging local peer %d!\n", peer_id);
        pnode.fDisconnect = true;
        return true;
    }
    
    LogPrintf("Disconnecting and discouraging peer %d!\n", peer_id);
    if (m_banman) m_banman->Discourage(pnode.addr);
    m_connman.DisconnectNode(pnode.addr);
    return true;
}
bool PeerManager::ProcessMessages(CNode* pfrom, std::atomic<bool>& interruptMsgProc)
{
    bool fMoreWork = false;
    if (!pfrom->vRecvGetData.empty())
        ProcessGetData(*pfrom, m_chainparams, m_connman, m_mempool, interruptMsgProc);
    if (!pfrom->orphan_work_set.empty()) {
        LOCK2(cs_main, g_cs_orphans);
        ProcessOrphanTx(pfrom->orphan_work_set);
    }
    if (pfrom->fDisconnect)
        return false;
    
    
    if (!pfrom->vRecvGetData.empty()) return true;
    if (!pfrom->orphan_work_set.empty()) return true;
    
    if (pfrom->fPauseSend)
        return false;