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
{
    const uint256& hash = tx->GetHash();
    if (mapOrphanTransactions.count(hash))
        return false;
    
    
    
    
    
    
    
    unsigned int sz = GetTransactionWeight(*tx);
    if (sz > MAX_STANDARD_TX_WEIGHT)
    {
        LogPrint(BCLog::MEMPOOL, "ignoring large orphan tx (size: %u, hash: %s)\n", sz, hash.ToString());
        return false;
    }
    auto ret = mapOrphanTransactions.emplace(hash, COrphanTx{tx, peer, GetTime() + ORPHAN_TX_EXPIRE_TIME, g_orphan_list.size()});
    assert(ret.second);
    g_orphan_list.push_back(ret.first);
    
    g_orphans_by_wtxid.emplace(tx->GetWitnessHash(), ret.first);
    for (const CTxIn& txin : tx->vin) {
        mapOrphanTransactionsByPrev[txin.prevout].insert(ret.first);
    }
    AddToCompactExtraTransactions(tx);
    LogPrint(BCLog::MEMPOOL, "stored orphan tx %s (mapsz %u outsz %u)\n", hash.ToString(),
             mapOrphanTransactions.size(), mapOrphanTransactionsByPrev.size());
    return true;