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
MaybePunishNodeForBlock(pfrom.GetId(), state, via_compact_block, "invalid header received");
            return;
        }
    }
    {
        LOCK(cs_main);
        CNodeState *nodestate = State(pfrom.GetId());
        if (nodestate->nUnconnectingHeaders > 0) {
            LogPrint(BCLog::NET, "peer=%d: resetting nUnconnectingHeaders (%d -> 0)\n", pfrom.GetId(), nodestate->nUnconnectingHeaders);
        }
        nodestate->nUnconnectingHeaders = 0;
        assert(pindexLast);
        UpdateBlockAvailability(pfrom.GetId(), pindexLast->GetBlockHash());
        
        
        
        if (received_new_header && pindexLast->nChainWork > ::ChainActive().Tip()->nChainWork) {
            nodestate->m_last_block_announcement = GetTime();
        }
        if (nCount == MAX_HEADERS_RESULTS) {
            
            
            
            LogPrint(BCLog::NET, "more getheaders (%d) to end to peer=%d (startheight:%d)\n", pindexLast->nHeight, pfrom.GetId(), pfrom.nStartingHeight);
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, ::ChainActive().GetLocator(pindexLast), uint256()));
        }
        bool fCanDirectFetch = CanDirectFetch(m_chainparams.GetConsensus());
        
        
        if (fCanDirectFetch && pindexLast->IsValid(BLOCK_VALID_TREE) && ::ChainActive().Tip()->nChainWork <= pindexLast->nChainWork) {