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
* @return                      True if the request can be serviced.
 */
static bool PrepareBlockFilterRequest(CNode& peer, const CChainParams& chain_params,
                                      BlockFilterType filter_type, uint32_t start_height,
                                      const uint256& stop_hash, uint32_t max_height_diff,
                                      const CBlockIndex*& stop_index,
                                      BlockFilterIndex*& filter_index)
{
    const bool supported_filter_type =
        (filter_type == BlockFilterType::BASIC &&
         (peer.GetLocalServices() & NODE_COMPACT_FILTERS));
    if (!supported_filter_type) {
        LogPrint(BCLog::NET, "peer %d requested unsupported block filter type: %d\n",
                 peer.GetId(), static_cast<uint8_t>(filter_type));
        peer.fDisconnect = true;
        return false;
    }
    {
        LOCK(cs_main);
        stop_index = LookupBlockIndex(stop_hash);
        
        if (!stop_index || !BlockRequestAllowed(stop_index, chain_params.GetConsensus())) {
            LogPrint(BCLog::NET, "peer %d requested invalid block hash: %s\n",
                     peer.GetId(), stop_hash.ToString());
            peer.fDisconnect = true;
            return false;
        }
    }
    uint32_t stop_height = stop_index->nHeight;
    if (start_height > stop_height) {