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
bool bPingFinished = false;
        std::string sProblem;
        if (nAvail >= sizeof(nonce)) {
            vRecv >> nonce;
            
            if (pfrom.nPingNonceSent != 0) {
                if (nonce == pfrom.nPingNonceSent) {
                    
                    bPingFinished = true;
                    const auto ping_time = ping_end - pfrom.m_ping_start.load();
                    if (ping_time.count() > 0) {
                        
                        pfrom.nPingUsecTime = count_microseconds(ping_time);
                        pfrom.nMinPingUsecTime = std::min(pfrom.nMinPingUsecTime.load(), count_microseconds(ping_time));
                    } else {
                        
                        sProblem = "Timing mishap";
                    }
                } else {
                    
                    sProblem = "Nonce mismatch";
                    if (nonce == 0) {
                        
                        bPingFinished = true;
                        sProblem = "Nonce zero";
                    }
                }
            } else {
                sProblem = "Unsolicited pong without ping";
            }