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
{
                            
                            while (!vRelayExpiration.empty() && vRelayExpiration.front().first < nNow)
                            {
                                mapRelay.erase(vRelayExpiration.front().second);
                                vRelayExpiration.pop_front();
                            }
                            auto ret = mapRelay.emplace(txid, std::move(txinfo.tx));
                            if (ret.second) {
                                vRelayExpiration.emplace_back(nNow + std::chrono::microseconds{RELAY_TX_CACHE_TIME}.count(), ret.first);
                            }
                            
                            auto ret2 = mapRelay.emplace(wtxid, ret.first->second);
                            if (ret2.second) {
                                vRelayExpiration.emplace_back(nNow + std::chrono::microseconds{RELAY_TX_CACHE_TIME}.count(), ret2.first);
                            }
                        }
                        if (vInv.size() == MAX_INV_SZ) {
                            m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                            vInv.clear();
                        }
                        pto->m_tx_relay->filterInventoryKnown.insert(hash);
                        if (hash != txid) {
                            
                            
                            
                            
                            
                            pto->m_tx_relay->filterInventoryKnown.insert(txid);
                        }