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 (it != pfrom.vRecvGetData.end() && !pfrom.fPauseSend) {
        const CInv &inv = *it++;
        if (inv.IsGenBlkMsg()) {
            ProcessGetBlockData(pfrom, chainparams, inv, connman);
        }
        
        
    }
    pfrom.vRecvGetData.erase(pfrom.vRecvGetData.begin(), it);
    if (!vNotFound.empty()) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::NOTFOUND, vNotFound));
    }
}
static uint32_t GetFetchFlags(const CNode& pfrom) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {