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
{
    AssertLockHeld(cs_main);
    CNodeState &state = *State(pto.GetId());
    const CNetMsgMaker msgMaker(pto.GetCommonVersion());
    if (!state.m_chain_sync.m_protect && pto.IsOutboundOrBlockRelayConn() && state.fSyncStarted) {
        
        
        
        
        
        
        if (state.pindexBestKnownBlock != nullptr && state.pindexBestKnownBlock->nChainWork >= ::ChainActive().Tip()->nChainWork) {
            if (state.m_chain_sync.m_timeout != 0) {
                state.m_chain_sync.m_timeout = 0;
                state.m_chain_sync.m_work_header = nullptr;
                state.m_chain_sync.m_sent_getheaders = false;
            }
        } else if (state.m_chain_sync.m_timeout == 0 || (state.m_chain_sync.m_work_header != nullptr && state.pindexBestKnownBlock != nullptr && state.pindexBestKnownBlock->nChainWork >= state.m_chain_sync.m_work_header->nChainWork)) {