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
if (pfrom.IsInboundConn() && !m_connman.CheckIncomingNonce(nNonce))
        {
            LogPrintf("connected to self at %s, disconnecting\n", pfrom.addr.ToString());
            pfrom.fDisconnect = true;
            return;
        }
        if (pfrom.IsInboundConn() && addrMe.IsRoutable())
        {
            SeenLocal(addrMe);
        }
        
        if (pfrom.IsInboundConn())
            PushNodeVersion(pfrom, m_connman, GetAdjustedTime());
        
        const int greatest_common_version = std::min(nVersion, PROTOCOL_VERSION);
        pfrom.SetCommonVersion(greatest_common_version);
        pfrom.nVersion = nVersion;
        if (greatest_common_version >= WTXID_RELAY_VERSION) {
            m_connman.PushMessage(&pfrom, CNetMsgMaker(greatest_common_version).Make(NetMsgType::WTXIDRELAY));
        }
        m_connman.PushMessage(&pfrom, CNetMsgMaker(greatest_common_version).Make(NetMsgType::VERACK));
        pfrom.nServices = nServices;
        pfrom.SetAddrLocal(addrMe);
        {
            LOCK(pfrom.cs_SubVer);
            pfrom.cleanSubVer = cleanSubVer;
        }
        pfrom.nStartingHeight = nStartingHeight;
        
        pfrom.fClient = (!(nServices & NODE_NETWORK) && !(nServices & NODE_NETWORK_LIMITED));