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
LogPrint(BCLog::NET, "Ignore block request below NODE_NETWORK_LIMITED threshold from peer=%d\n", pfrom.GetId());
        
        pfrom.fDisconnect = true;
        send = false;
    }
    
    
    if (send && (pindex->nStatus & BLOCK_HAVE_DATA))
    {
        std::shared_ptr<const CBlock> pblock;
        if (a_recent_block && a_recent_block->GetHash() == pindex->GetBlockHash()) {
            pblock = a_recent_block;
        } else if (inv.IsMsgWitnessBlk()) {
            
            
            std::vector<uint8_t> block_data;
            if (!ReadRawBlockFromDisk(block_data, pindex, chainparams.MessageStart())) {
                assert(!"cannot load block from disk");
            }
            connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::BLOCK, MakeSpan(block_data)));
            
        } else {
            
            std::shared_ptr<CBlock> pblockRead = std::make_shared<CBlock>();
            if (!ReadBlockFromDisk(*pblockRead, pindex, consensusParams))
                assert(!"cannot load block from disk");
            pblock = pblockRead;
        }
        if (pblock) {
            if (inv.IsMsgBlk()) {