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
*  relayed before unconditional relay from the mempool kicks in. This is only a
 *  lower bound, and it should be larger to account for higher inv rate to outbound
 *  peers, and random variations in the broadcast mechanism. */
static_assert(INVENTORY_MAX_RECENT_RELAY >= INVENTORY_BROADCAST_PER_SECOND * UNCONDITIONAL_RELAY_DELAY / std::chrono::seconds{1}, "INVENTORY_RELAY_MAX too low");
static constexpr unsigned int AVG_FEEFILTER_BROADCAST_INTERVAL = 10 * 60;
static constexpr unsigned int MAX_FEEFILTER_CHANGE_DELAY = 5 * 60;
static constexpr uint32_t MAX_GETCFILTERS_SIZE = 1000;
static constexpr uint32_t MAX_GETCFHEADERS_SIZE = 2000;
static constexpr size_t MAX_PCT_ADDR_TO_SEND = 23;
struct COrphanTx {
    
    CTransactionRef tx;
    NodeId fromPeer;
    int64_t nTimeExpire;
    size_t list_pos;
};
RecursiveMutex g_cs_orphans;
/** Map from txid to orphan transaction record. Limited by
 *  -maxorphantx/DEFAULT_MAX_ORPHAN_TRANSACTIONS */
std::map<uint256, COrphanTx> mapOrphanTransactions GUARDED_BY(g_cs_orphans);
/** Index from wtxid into the mapOrphanTransactions to lookup orphan
 *  transactions using their witness ids. */
std::map<uint256, std::map<uint256, COrphanTx>::iterator> g_orphans_by_wtxid GUARDED_BY(g_cs_orphans);
void EraseOrphansFor(NodeId peer);
namespace {
    
    int nSyncStarted GUARDED_BY(cs_main) = 0;
    /**
     * Sources of received blocks, saved to be able punish them when processing
     * happens afterwards.